Subject: Re: UK wants to arrest, extradite US citizens...
The UK could swear out an arrest warrant, hold a trial, reach a verdict and pronounce a sentence against any US citizen they want, all in absentia. While that US citizen would be in hot water if they ever dropped in the UK - where they would be subject to arrest - no sane US government would extradite on such a request.

True - and the UK likely wouldn't request extradition from the US, either. Most extradition treaties only permit extradition for actions that are a crime in both countries. I think they would recognize that the consequences for Musk would be relatively limited, and mostly serve to declare him persona non grata in the UK and any other countries that have reciprocal agreements with the UK that would be affected.