Trump's opinion of London is precisely as relevant as our opinion of Trump.
There are Sharia courts in Britain. Also Ecclesiastical courts for Church of England matters and Beth Din for Jews. Quite possibly Hindus, Sikhs and others have their own versions. And, outside religion, we may agree to be bound by the decision of an Arbitrator, outside the court system.
No-one except a few extreme religious nuts seriously proposes giving any of these jurisdiction over anyone who doesn't consent to it. Certainly Kahn doesn't.
Yes, some of his policies, particularly the Emission Zones, have been annoying and inconvenient. But they are probably necessary. And were instigated by a Tory Mayor anyway.
But, as it seems increasingly apparent that it's just too inconvenient to do anything about global warming so we're just going to deny it, perhaps it will all get reversed!
A drop in the ocean in the great schemes of things....but replicated by how many more

