In the second case, it was not about misgendering someone - they were accused of a campaign of persistent harassment, something which the Daily Mail fails to mention except as a minor aside near the end of the article (not untypical of the Mail, naturally).
The Linehan case was debatable, and the approach taken probably wrong in some forms by the police (as admitted) but they were not arrested for simply voicing an opinion, but for behaviour which was sufficiently threatening and/or assaulting for the police to believe that a crime may have been committed and thus warrant further action.
There are cases of overreach, that applies outside of the speech issue as well - and indeed for any country with a reasonably effective policing system, it's never perfect. But these cases are not the simple slam-dunk that people will try and paint them as.