Putting aside whether or not he'd like it...Wouldn't a space marine know that engaging someone like that one on one isn't really likely to end well for him? 

I mean, the character's based on the Dark Crusade commander, so...you're looking at someone who knows you're coming, can turn invisible (for balance's sake, I'll be saying that running the stealth field and weapon systems at the same time isn't an option), has a gun that (on average) does REALLY bad things to Land Raiders and is more than happy to avoid fighting if you are.