I think it's a bad idea to say this every time a new discussion about sex/gender comes up. If each time such a post is made, someone posts "there is no way this will go well" and everyone stops posting, then it is literally impossible for the conversation to go anywhere. I think it's much more valuable to have bad posts if those enable good posts to also exist, instead of just having no posts on the topic.

At the very least, wait UNTIL the thread descends into shittiness, and then lock it, instead of preemptively banning on all conversation on a subject that is vitally important to the happiness of many.