I don't see anything unethical with the question, again, it was reported in the public arena.
It's Ireland's job to push buttons, sorry. Anyone that has been in a locker room as a athlete at any level knows, it's not the 1st time Dez had to have dealt with that question, or comments about his moms. Ireland may have simply, in his mind, been trying to not bring a cancer into his locker room. It's an excellent way to see what's going on in Dez's mind.
I think you may be missing the point however. Ireland knew the answer to question, he was looking for Dez's response. If Dez couldn't handle a question like that, he has no business playing in the NFL IMO. As PRO he could have possibly faced even more probing questions from the press. He handled it, well sort of. If Dez really wanted to get the upper hand, he simply would have never mentioned it once he left the draft interview room.