Sure, but the subject is the same; it’s still posting about ‘such and such’, and the rule here is about subject, not framing.
If I need to put a content warning on a topic that could be inflammatory if someone appended ‘you stupid fuck’ to the end of it, then I need to put a content warning on everything, rendering it useless.
I respect the intent behind this, but I’ve been round internet (and pre-internet) discussion forums since the 80s, and this approach just muddies the water.