I do agree that we all have a responsibility to manage our own mental health to some extent. We can't expect the world around us to hide away anything and everything that might potentially cause us distress. If you struggle with your mental health to the extent that you find certain topics triggering even if you just see the thread title, then it makes sense for you to avoid general forums in which any topic can be discussed. It is inevitable that significant world events will be reflected in such forums, and even if a separate board is created, you may still be exposed to threads that have accidentally or deliberately been put in the wrong place.
You want MNHQ to protect you by removing all reference to those triggering topics from the general forums, but you could just as easily remove yourself from the general boards in order to focus on what you want to talk about. Yes, I get you have some degree of fomo about missing out on the more lighthearted threads on AIBU or Chat, but there is nothing to stop you from starting your own lighthearted threads elsewhere. And why should the open nature of the miscellaneous boards be restricted for everyone because you don't want to do that?
If we decide to cleanse certain topics from the general forums because some people are triggered by seeing the titles, then surely there are a whole lot more topics that we would also have to ban from those general forums because other people might find them triggering. Pregnancy, for example. Climate change. Racism. Cancer. Bereavement. And so on. The miscellaneous boards will be reduced to little other than parking threads and MIL threads, and I expect someone will be along sooner or later because they find those triggering.
We have been repeatedly told by campaigners for a separate board that MN is not just about Chat and AIBU. That people can post in the topics that interest them. So why not follow your own advice?