And to be perfectly honest, I’m all for it, especially if they’ve done this (and will do this more broadly, as you suggest) despite expecting to take a substantial ‘hit’ to their bottom line.
I mean I want to say they should let that happen, but the US is toothless in that the population wouldn't revolt if it happened. Twitter would end but nothing would change.
But it's not going to go there, Twitter will sit with the government, they'll make a deal, some palms will be greased and they will bow to their government overlords.
Companies are fucky like that; on the one hand they influence public discourse and voting behaviour, on the other they're morally flexible and will grovel for their government masters if they get to earn money there (see also Google and China, Hollywood films and China, etc).
They're an American company and can choose to justify fact-checking only the US President if they want. It's not like hypocrisy has bothered them in the past; it clearly didn't bother them when the US elected a troll and they fixed the glitch of their own TOS suggesting he be banned from their service by modifying the TOS to have a carve-out for "newsworthiness."