Nothing is stopping the community from talking about bad things. If you want to opt out of certain topics, that doesn't stop anyone from doing their own thing, it just stops you from seeing them. If you choose to allowlist your friends, you'll see whatever they post. If you blanket hide any posts that mention something, that's entirely your prerogative.
You cant have your own community banned for talking about something bad that happened to them.
I would be curious how that scenario plays out.
Perhaps the content is only greyed out. What do you do about users though? Is their content greyed out?