Why does it matter who the post's author is? If it is a useful on-topic question; it remains a useful on-topic question no matter who has asked it. If it isn't, then downvote and/or vote to close it so that it may be deleted later. It is wrong to judge questions/answers differently based on who is the author.
If you wouldn't downvote or close a question if it had been asked by somebody else, then you should not downvote or close the question.
If somebody produces a stream of good questions that represent actual on-topicon-topic problems (about understanding mathematical concepts and theorems, hints on mathematical problems, history and development of mathematics, solving mathematical puzzles, software that mathematicians useunderstanding mathematical concepts and theorems, hints on mathematical problems, history and development of mathematics, solving mathematical puzzles, software that mathematicians use) with good answers, then the more the better.