Do we even know that designating a player wipes out the no-trade? I'm quite confident that waiving him without designating him won't make the no-trade go away. And if you can't trade the guy while he's designated and waiting for assignment, then the only way the logistics work is for Team B to claim the player, have the claim succeed, and then after the fact Team A sends cash and prospects to team B for nothing at all, which is collusive in my opinion (ie, agree with pjf).
Basically agree with pjf and Mike that if you're above board with this and the world is OK with it, whatever, but that I wouldn't be OK with it.