I don't know if you get to have it both ways without trampling on WeChat's first amendment rights as well as those of their users unless you pass data privacy laws for US citizens/persons (which might have first amendment implications anyway) and deal with WeChat through whatever mechanisms this newly-passed (and yet-to-be created) privacy law contains.
So either WeChat, Facebook, and whoever can facilitate protected speech among their users (in this case you're protecting the users specifically) or the various platforms are treated as publishers which still wouldn't allow the US government to prevent or compel speech (protecting the organization).
It's possible they can get away with banning the payment portions of the app but the outright ban appears to be prior restraint of free speech by the government.
So either WeChat, Facebook, and whoever can facilitate protected speech among their users (in this case you're protecting the users specifically) or the various platforms are treated as publishers which still wouldn't allow the US government to prevent or compel speech (protecting the organization).
It's possible they can get away with banning the payment portions of the app but the outright ban appears to be prior restraint of free speech by the government.