I sort of hate that the best current Celtic is a jerk
I must say that this doesn't really bother me. He's a jerk, but he's our jerk. KG is / was kind of a jerk, at least in terms of the over the top on-court trash talking. From what I've read, Bird was kind of a jerk. Kobe is an epic jerk. MJ was the biggest jerk of them all.
In all cases I think that quality comes from being extremely competitive and having high standards for oneself and ones teammates. I can get behind that. I like that a lot better than Jeff Green's apparent "I'm down with whatever" persona. I also like it much better than the "pretty boy / primadona" attitude you see some of the younger, entitled stars putting on -- Kyrie Irving and Blake Griffin come to mind.
As for the allegations against Sullinger, I have to admit I don't think about it much. Perhaps it should bother me more. I try to keep some separation between what happens off-court and what happens on it, but sometimes that attitude can get you into trouble. The off-court stuff is more important than the on-court stuff in the bigger picture, after all.
In any case, I enjoy watching Sullinger play. His post game and rebounding are very refreshing after watching this team lack both for most of the KG era. I also like that he's a guy who has fire and grit on the court -- he kind of reminds me of Perk in that respect -- but he is generally friendly and jovial off the court.