Got a source on this one?
Supporting Palestine in the UK has never been illegal. Supporting the specific group "Palestine Action" has been as they were for a while a proscribed terrorist organisation due to what was (IMHO) some property crimes committed against defense contractors by some of their members. Totally wrong, and has now been struck down in the courts, but saying "you can't support palestine" is also wrong.
> Thousands of people arrested every year over tweets.
The source I saw on this one had clear examples of violent threats and calls to set buildings full of people on fire, so I'm not sure this is clear either.