I agree with both of you, there is a lot of value in posts being able to be seen outside of community's as well. That is a good thing.
The only thing that would be better is if the user could control that behavior and choose which posts to show on main and which ones to keep as a community-only post.
> For this “4549” event it can be the exact same thing just like the existing kind 1 with “a” tag, but it’s a community only post.
Yeah exactly. The only reason I suggest having it be a "post request" that wraps an event (just like "post approval") is so that all the existing event kinds (e.g. long form, media) and whatever will be invented in the future is compatible with communities. Cause it would be boring is communities could only work with basic text notes, right?