This is tax payer sponsored league.
Freedom of Association would seem to imply you’re free to join the league or not - and I’ve heard no claims to the contrary. When you’re in a sports league, though, you follow their rules. Choosing who you play does not appear to be a freedom of association issue (for league games, not casual ones.)
Sorry, I missed that. But she’s still an azz for trying to force anyone to play against her.