The market hasn't shaped up the way his side hoped and it seems like it will work to the Celts benefit.
It looks like it will, for this year.
Long term, I'm not sure that it will. I see it a lot like salary arbitration in MLB. That stuff can lead to hurt feelings that last. Marcus is probably particularly vulnerable to that, because 1) he runs high emotionally as a base line, and 2) he's dealing with his mother's cancer, which leaves most people emotionally raw.
If there's any way to mitigate hurt feelings, I'd explore it.
If it 'guaranteed' his return next year, then yeah, obviously; however, I would guess that he will probably take the most money offered next year whether it is from the Cs or another team.
It might be nice to give him that extra $2M, but I would prefer to sign another vet minimum player and hang on to Bird with that money. Smart is going to be upset if he doesn't get a big deal this offseason, regardless.
Also - and this certainly doesn't benefit Smart - by signing Bird and a vet min player, you add more quality to the roster which may cut into Smart's minutes possibly making him even more affordable next year. It really is a win-win for the Cs.