Such questions are meaningful to the people that ask them. Someone who asks "can God make a square circle?" is unlikely to consider it to be equivalent to asking "gjqrio jtioajfs dklfjl?" (ie. a sentence made of words which really are meaningless)

You can claim that these questions are meaningless, but then you have to prove why.. and there's been no such proof, just an assertion.

Maybe you intended a proof by definition? That is to say that you want to maintain that any question that involves a contradiction is meaningless by definition? Well, that's an assumption, and the person you're speaking with doesn't have to grant that assumption or agree to that definition.