There's a difference between saying that you disagree with the way that a country is being run, and wanting to be violent or pursue criminal activity against that country or its people.

What you're missing is that the former should be legal in any democracy (and is in the UK), and the latter shouldn't be legal anywhere (and isn't in the UK).

You're claiming the UK lacks "freedom of speech" because it doesn't allow people to incite violence online, while saying the USA has free speech, despite it seemingly rejecting visitors for legal political speech.

I know which side of the pond I'd rather be on.