We are not.
It is my growing personal conviction that there's a culture clash between this place and our particular group. Every single time we've tried to engage with people here, it's ended up exploding in our faces. I'm woman enough to admit that some of that is likely on us - no one in the Alliance is a particularly meek or amiable personality on the best of days (there's a reason I act as the group's spokesman), but a larger part of it is on folks who seem to be surprised that we're not willing to job our faces off to inflate win counts around here and grovel at the feet of Da Champs until we've 'earned our place'.
I think you're misconstruing interactions you've had with specific people with Guild's Arena section as a community. This is problematic because:
1. The people in question are probably more tied to the TZDL, given the back and forth that has occurred. The TZDL, in terms of staffing and numerous people participating, are not "from" Guild, so attributing any interactions you've had with them to the community here isn't really accurate. This is, admittedly, a guess. For all I know, maybe one of the "home field" players like Melon or LeeRoy jumped down your throat at some point in the past. I can't really say, but I do know that the most recent friction hasn't been between you and Guild players, it's been between you and Zone players.
2. Guild's "home" population is very small and unlikely to be uniform in attitude. There's, what, maybe a dozen home-field players that are regularly active? "Regularly" being a relative term, considering the dearth of posting that was going on prior to the TZDL. It's somewhat difficult to imagine that a nearly dead community could muster up the wherewithal to make a group of people unwelcome when they can't necessarily dredge up the time or effort to keep their community active.
I'm from off-site too and I've never had any of the issues you've described with the people on Guild, and I'm pretty certain that it has nothing to do with any difference in personality, being that a) people in most fighting communities tend to be more assertive and argumentative as a general rule, so it's not as though your group is unique in that regard and b) I'm easily capable of being as acerbic and abrasive as anyone and it has had no real effect on how people perceive me.
RPGuild's Arena doesn't really seem to enjoy the sorts of fights we do, and we don't enjoy the sorts of fights we keep finding here. Everyone in the Alliance cut their teeth on a tier of combat where star systems were legitimate targets, and we all like savoring combat and drawing out a fight for twenty, thirty, or more turns over dozens of exchanges. A true display of each fighter's versatility, adaptability, inventiveness, and perseverance in the face of unrelenting, unflagging war. One Punch-y instagib five-post fights are not considered marks of skill or distinction for us; they're considered marks of scorn for a player considered beneath the attention and effort required of a proper fight.
We've decided it would likely be for the best for us to withdraw from play here. You don't want us here, and we don't particularly feel like being here anymore. Why keep pretending otherwise?
This seems like a personal failure, if I'm being frank. Aside from being inaccurate -- having judged several fights from RPGuild players including LeeRoy, Melon, Pollen, and others, I can say with a relative degree of certitude that their fights aren't particularly short nor geared towards being ended as quickly as possible -- it's also not especially logical or conducive to actually gaining anything from cross-community interaction. If you're going to participate in cross-site play, you generally follow the house rules until you've established some kind of rapport with the other community. You don't show up to someone else's game night and then demand they play your game. You play theirs, and if things go well then you can suggest your own game.
It's illogical to hop across a figurative pond to someone else's community and expect them to play by your rules, your preferences, and your communal mindset, and taking that approach effectively dooms you from the start. If you're not willing to adapt to the communities you travel in, then the onus for any failure-to-launch is really on you, not on the community. You can't expect a community to play differently for a complete group of strangers. If you want to enter a new community and get people to play your way, you generally have to play their way first.
I should know, being that I've been active on Gaia, NSider, Valucre, RPGuild, in the TZDL, and in numerous other communities, all of which have varying rulesets. In every instance, I've adapted myself to that community's way of doing things, while also explaining my own community's approach. Because I've been willing to adapt, I can in turn get people to adapt to my way of play. I can go into any of those communities -- those that are still extant, at any rate -- and say "Hey, I want a fight, and I'd like to fight according to my rules and preferences." I'd get plenty of people willing to do so, because if I jumped into one of their events, I'd adapt to their approach.
Roleplay is a fluid hobby. It has minimal rules, upon which we can build a nearly endless number of variant rulesets and approaches. If you want to play across multiple communities, you have to be adaptable. If you you're unable to adapt, or if you're dogmatic about how you want your roleplay to be done, then community-hopping isn't really for you, and RPGuild isn't to blame for that.
If you can't or won't adapt to the communities you come into contact with, then it might be best that you don't explore other communities because that inflexibility will just create impasse after impasse and you'll never really get anything for your efforts. That being said, I think it behooves anyone who sincerely gives a flat fuck about this hobby to push themselves towards being as flexible and fluid as possible, because it's the only viable way to create cross-community connections that are going to allow roleplay to grow and flourish.
Being dogmatic and/or isolationist only leads to one thing: stagnant, shrinking communities.