You have to draw the line somewhere. Enough is enough. They've been nothing but cooperative until now and all the goodwill has been taken advantage of and painted as weakness. It's about damn time they switched from passive to active pushback.
And it's not going to provide anti-EU people with anything they haven't dreamed up themselves long ago. Have you listened to anti-EU propaganda? It's mostly demented, wild conspiracies.
The EU is an association of like-minded societies. If Hungary doesn't feel like it belongs anymore they can start considering withdrawing.