Because clubs are in charge of stadium bans
It's like that in England and every other country too.
Also it is public knowledge as he just tweeted it
No, it isn't just in hands of club everywhere.
La Liga is a union of 42 clubs, if a club decides to not act rightfully, it means it hurts the brand and the other 41 clubs.
If Valencia says they don't ban the fans, it hurts other clubs. It can push sponsors and fans away, make financial loss to everyone.
Every league has disciplinary power over their clubs, which was agreed by them in advance anyway, so La Liga didn't act. They just said empty words.
What happened to those 8 "thugs" football wise? is it a public knowledge? Has any of clubs who chanted racist stuff get punished by Liga? doesn't seem so and he doesn't address it.
He is just acting like it is something that should be dealt internally, when it shouldn't be. Vini has every right to reject those silly meetings Tebas is inviting him for