The UK has it's own standards for speech. They don't need to adhere to the free speech absolutism of the United States. This would be unacceptable in the United States, but many places do not protect racist speech. Theres good arguments on both sides. We'll see which works out better in the long run.

I’m a staunch advocate of free speech, but I think that a specific and credible threat of violence should be considered a crime (assault) and subject to prosecution, even though it’s “just words”.

Words can be extremely damaging. The US has libel and slander laws. What's so different about hate speech? It's harmful, almost as harmful as some forms of physical abuse.

Don't forget that most domestic abuse and physical abuse starts as verbal abuse, so criminalising that is not unreasonable

Especially words against willing public figures, living above average lives