Absolutely not the case. This is just what overly online people think.

Oh for gods sake, can we stop this nonsense mad twitter trope spreading through HN. Having been a cop in the UK, we will happily got nick a robber if they're on the move and tell us where they are, and we don't arrest people for "wrong thought" on twitter unless that happens to be repeatedly messaging your ex and telling her about how you're going to do murder them.

yes, some of my stupid colleagues will once in a blue moon arrest people for twitter nonsense, but that barely ever happens which is why it makes the news and they pretty much never get convicted.