You are absolutely right. Hungary is a sovereign country. If they don't like their citizens having access to a particular private platform/medium, they can block access to it. It's very simple. The same way it's done with everything else. If a country doesn't like a particular book, they ban imports into their territory. If they don't like their citizens having ability to catch a TV/radio transmission from a neighboring "enemy" country, they can jam the signal. They don't ask the publisher from that other country to modify the contents. So, if they don't like Facebook operating in their territory, they can copy what China does and get rid of it. But once a country decides to do such things, they can no longer be considered a democracy.

Facebook should not accept instructions from Hungarian government. Now it's "Please don't remove videos from our minister", tomorrow it will be "Please immediately delete any bad comments about our government. Oh, and that opposition candidate's page? Delete that too"

Facebook's community standards should not be universally accepted. Does anyone force Hungarian people to use Facebook and accept their community standards? No. But if they freely choose to use it, of course they are expected to accept the rules of the community they willingly chose to participate in.

I am not a Hungarian, and I don't care what the Hungarian government is doing within their own country. If they want they can censor newspapers, ban TV shows on local media, close the borders, not have foreigners in their country, whatever. But they shouldn't influence foreign media the same way that they cannot ban a TV show airing on some Croatian television because Hungarians near the border can catch it...