He doesn't have to be nice. He just doesn't have to be a dick. It's pretty simple actually. When he goes out of his way to embarrass people it makes me wonder how he treats people that actually have an impact on his job performance (ie. other teams/GMs). If a GM called and made a lowball offer for Dame, does Neil laugh him off the phone? Does he give some sort of proper but somewhat condescending answer that makes the other person less likely to deal with him in the future? Reports are that some teams did not like dealing with Ainge towards the end because of Ainge's personality. I think the people aspect definitely plays a part in your job performance, and I'm questioning that part for Neil.
Also, how hard is it to just not be a dick? He does this twice a year, it's really not asking that much. Nobody is telling him to be buddy buddy and be a gentleman. Just don't go out of your way to act like an ass. I swear, if some people acted like this in your jobs, would you have a good impression of them as people?