In less aggressive terms, if you want people to interact with you it needs to be a bit more organic. From the perspective of the other characters in the store, there's just a disagreement going on in the background between a Master and their Servant. That's not anything unexpected, and at the moment Mordred and Lancelot are about to recognize one another while Jason is trying to get an apology for having soda spit all over him, bringing all those characters into direct contact.

If Nobu had, I don't know, bumped into Mordred and made her dump her soda [i]onto[/i] Lancelot or Seria or something, that would have been funny and more organic.

It also would have given the characters something to do in relation to Nobu, rather then like... just watching an argument. ^^;