I don't really know what political capital Musk could make out of it? He's going to be in charge of government efficiency not foreign affairs. Also, for me, he's not commenting on British politics. He's commenting on a British crime. We comment on American crimes all the time. Jess Philips, Kier Starmer, Sadiq Khan, all had things to say in condemnation of the racist murder of George Floyd. And this isn't the murder of one person, but thousands of young lives destroyed and innocence annihilated. Of course I'd expect people from other countries to comment.
I just don't understand the outrage, because big businessmen and political figures from overseas comment on British affairs all the time and always have. George Soros famously donated millions to Remain during the Brexit campaign, that to me was much more of a clear example of foreign interference, and yes some Brexiters were angry but not to this extent.
I understand what you are saying, that people can be angry about two things at once, but I maintain that many posters on this and related threads honestly seem angrier at Musk than they do at the rapists and the supine people in authority who didn't bother to try to stop it all happening. And I maintain that I do not understand how any human being could reserve more anger for Musk, who is commenting, than the rapists themselves, who perpetrated.