The question in my mind; would you rather give up a second rounder for Kurt Thomas, or sign Dan Gadzuric off the street? Either way, you'd have to let someone go for the roster spot. Gadz is more of an athletic presence, not much of a defensive rebounder as I recall but pretty good on the offensive glass. KT has always been a strong defender/rebounder. No clue how much game he has left, if any.
Neither would be a difference maker, but either would help.
KT would cost a draft pick. Most second-rounders don't pan out, but there's always the chance of getting another guy like Ryan Gomes in the middle of the second. I wouldn't toss them away needlessly.