I have expressed my opinion before and I reiterate here. Migrating to math SE (or anywhere else) is not ethically correct. We can only decide that the question is bad for MO, not that it is "more appropriate" for another site. As for math SE, from what I heard, it is populated by undergraduate students trying to cheat by posting their homework questions, and by mathematicians helping the cheating. Perhaps I am wrong, but if I am correct, migrating a question there would be even more wrong.