Unless Ainge has some fetish for point-guards that can't shoot, I can't see how would Sessions suit the Celtics.
I'm not a fan of Sessions - extremely ball dominant, terrible shooter, mediocre defender, mediocre on the open court, one trick pony (high ballscreen -> penetration -> dish/kick out/finish/draws foul). He has a better reputation than this and his contract is relatively cheap, so I don't see the Wolves trading him for expirings in any case. They're taking in salary to add very mediocre players, why would they dump Sessions?