My dude.

Just don't.

Everyone else already knows that if there's only one mod, they own the forum, whether they originated it or not.

You can choose to pretend this fact has not existed since the nineties if you like, but you won't fool anyone but yourself.

If there's multiple mods, there's one that is still top mod, and counts as owning it, regardless of whether or not they use that ability.

If the forum is multi layered, like reddit, lemmy, and similar places, there will be someone that owns the site/service/instance, literally because they own the hardware it is run on. This has also always been the case as long as such layered forums have existed.

What you call "true free speech" is not true free speech, it is speech without consequences, and that does not exist anywhere in the world to any large extent.

The consequences may be minor, but even someone looking at you funny is a consequence of one's speech

this is a fact that has existed as long as language.

If you go into someone else's forum and do not follow the rules, assuming rules are available, it is your responsibility to either follow them, or assume that consequences will occur.

If the rules are not available, it's a shitty forum you should avoid anyway.