like I mentioned, there's tons of unlicensed doujin floating around japan being sold at cons and most companies, Toei included, do nothing. of course, there is a difference between japan and america, but fact is Toei is at worst tolerant of unlicensed undeserved merch sales.
what they don't like are shitshows and based on TFS, mockery. most doujins even ones poking fun at the source material do have a level of appreciation to it, from a japanese perspective.
TFS on the other hand is american made and comes from that perspective, which since its mocking can come off as rude and insulting.