edit: Are military actions against these countries targeting Muslim communities worse than removing immigration privileges of Muslim communities? I dunno how to approach this question...
And there are many who not only disagree with Trump, but are appalled at his persona. There was that big march and that whole "Not my president" thing. They are already primed to believe that Trump will attempt to turn the US into a fascist state. In that light they say this as Step 1 of the "US turns fascist" and they are reacting as though he is suggesting Step 10 Imprisoning political opponents. Because they "see" the path and are doing everything they can to stop it.
Of course it helps that "a muslim ban" is quite literally what Trump asked for according to Rudy Giuliani:
> So when he first announced it he said “Muslim ban.” He called me up, he said, “Put a commission together. Show me the right way to do it legally.” I put a commission together with judge Mukasey [Michael Mukasey, a former federal judge], with congressman McCaul [Texas Rep. Michael McCaul], Pete King [New York Rep. Peter King], a whole group of other very expert lawyers on this, and what we did is we focused on, instead of religion, danger—areas of the world that create danger for us. Which is a factual basis, not a religious basis. Perfectly legal, perfectly sensible. And that’s what the ban is based on. It’s not based on religion, it’s based on places where there are substantial evidence that people are sending terrorists into our country.
Very interesting
People outside the US are used to the US being far to our right, and it being relatively futile to do more than complain about these things. But Trump is seriously scaring people.