I'd rather post in an active community such as homeschooling than be perfectly spot-on for a topic of an otherwise dead community.
I can only admit, that activity in History community is about zero. But that does not provide a legit reason.
On the other hand, the subject of your intresting posts is pretty differ from Home'edding community topic. I used to see mods press 'mute' button in such cases. (Which frustrates me a lot -- if it is my post...) 😳
Not being able to find the community - and not wanting to search indefinitely should be a legit reason... and honestly, if I think it's a legit reason to not want to use a zero-support community, then that should be sufficient.
If home education mutes educational posts, then it's not much of a home ed community, in my opinion. If they do that, then I'll leave it to them... and go back to posting in The Terminal instead... or Ladies of Hive... I have other options. It's a pain to have to sort my posts to that degree all the time.