There’s been a lot of cases where the opposition is a bunch of US plants or worse so a charitable interpretation is they’re worried about that. A less charitable one is the one everyone has already posted: they’re tankies, ie left-wing authoritarians and like the authoritarian government.
For the record I’m holding off on having an opinion until I’ve read an analysis of the situation I trust, and I haven’t found one or had the time to look seriously. My opinion doesn’t really matter in this case anyway so I don’t think I’m in a hurry to find a correct position.