They don't really deny Slovakia's legitimacy, at least not officially because it was part of the deal to join nato to give up on those claims.

From Orbán most of these are a performance towards his different voter blocks. Even in a single talk he gives he swings between far left and far right rhetoric depending whom he wants to pander to.

Maybe he said something that I don't know about, but recently he even started to distance himself from the Hungarian minority parties in Slovakia in favor of Fico. It's all about staying in power and finding the right allies for it.