The Celtics are a young, young team. Brad Stevens is a young, inexperienced coach. The more veteran leadership that we can add to this team, the better.
Some of the best young talent on the team right now is found among the big men -- Sullinger, Olynyk, Faverani. The main weak point for all three of those guys is the defense. With KG gone, they could really use a guy who's been in the league for a while and has made a career pretty much solely out of being a solid post defender to teach them and show them how to prepare for games.
The Celtics have an open roster spot. I can't think of a better 15th man to add to this group than Jason Collins.
Add on top of that the fact that this Celtics team could really use some feel-good storylines this season. The wins are going to be few and far between. Rondo's return is probably at least a couple months away. Gerald Wallace is yapping to the media after every game, not really hiding the fact that he isn't happy to be here. Most outside observers have pronounced this a tanking team and basically moved on. Nothing to see here. Being the one team in the league that has the courage to hire Jason Collins after he came out this summer would be a nice little PR story to boost public opinion for the team as they embark on this "rebuilding" season.
The Celtics had Jason Collins here last season, so they already are familiar with him, and by all accounts he was well-liked around here. So what does the team have to lose? Let's bring him back. I'd rather have the media focused on that story instead of reading more quotes from Gerald Wallace after another loss to a mediocre team.