Depending on the cost, why not?
If Houston wants to get anything back, they have to field offers. A swap with Chicago for Noah would be probably the best player-centric trade for the Rockets. However, if they are just looking for a re-build, recognizing that either combination of Harden/Howard Harden/Noah isn't going to get them far in the WC, then Boston is the team to talk to as far as stacking some picks.
Brooklyn picks are obviously all out of the question. But I honestly have no issue in taking the gamble of sending them Lee's expiring, Jerebeko, our own first rounder (late teens/early twenties), and a couple 2nd rounders for Howard.
Worst case scenario, is Howard acts like a baby/sucks. The team is winning without the help of Lee/Jerebeko, so we can embarrass the hell out of Howard by benching him all season, if he acts like a little girl.
HOWEVER
His body-type and playing style is truly the missing piece for this team. Howard coming to Boston would also give him the opportunity to become "the man" if he so choses and has that ability to. If there's any coach who could get the most out of him, I think Stevens has a shot at it.
We are all talking about drafting either a rim-protector or a scoring wing. Other than Simmons or Labissiere, there isn't any "sure thing" type player coming up in this draft. So having Howard will at least allow for us to just take the BPA, assuming we don't get lucky and land that #1/#2 pick.
Is his contract a player or team option for next season? It would be nice to have him for next year, even if as one of the most amazing expiring contracts of the last decade if he's not a fit. But honestly, if it only costs us Lee and Jerebeko and a couple of picks, it's worth the risk. We won't even be able to roster all these draft picks if we keep them all. I think this is a gamble worth taking!