"In brief, around ten percent of the population of Slovakia is Hungarian-speaking, beyond which there are Ukrainian, Roma and other minorities. For all practical purposes, the new law eliminates all the minority languages from the public sphere. Yet even here there is a further discrimination - the small Czech minority is exempt from its restrictions."

In no way attempting to defend this language law but I think I can explain the last bit easily enough. There simply aren't many Slovaks living in Hungary or the Ukraine and the Roma don't control a state anywhere. But if Slovakia enacted something against the Czechs living in Slovakia the Czeck Republic could be expected to tit for tat against the Slovaks living there. It's what we humans do.