Both options should be possible.

Integrating into "setProps" will need a little more logic to implement, since the op is also available to mods. It'll be a matter of adding a check for permissions, but it's not complicated.

A custom JSON op like "setType" would need even less changes to current logic to implement.

My thoughts were that maybe it's more an issue of making a community "immutable" in that current members who like it the way it is still get to keep it, while a new one can always be created for a new purpose.