No ones saying there are 2 sets of laws only multiple ways in which those laws are applied. The same thing you're saying.
Sure they can, but they should then be accountable for what's on their platform. You cant on one hand say we are going to mediate what's being said on our platform and at the same time say you arent responsible for what's on our platform. When Facebook can be held liable for slander and defamation for things posted on its platform then they are free to censor whatever they want. These companies want their cake and to eat it too.
The government should never be involved with suppressing speech. Of any kind. Ever. Period.
That said, the US government was doing far more than asking for posts to be removed.
Why on earth would you ever want the Government doing what it was doing is beyond me.