National security law most certainly apply to foreigners, since its chiefly foreigners who are most active in endangering Chinese national security. Chinese nationals working for hostile foreign powers are just expendable useful idiots who will also get caught by the law, but the chief targets are the foreign agents who are the real ringleaders and masterminds.
It would make no sense for national security laws to have no powers against foreign nationals operating on Chinese soil. Indeed, that was why the likes of America were protesting the law, they couldn’t give two shits about the local useful idiots, as evidenced by they booting said idiots out when they went to the American embassy to beg for their masters to save them. But as soon as the new law came into effect and their own people’s arses were on the line, all the riots magically stopped.
On the specific case of Jimmy, well I think China has a clause established especially for traitors like him. Just because you got a foreign passport does not shield you from being treated like any other Chinese National. If ever there is a case where that should apply, Jimmy’s is the one.
That means that he can and should he tried as the traitor that he is.
Great news then, that China can still trial him for treason! Of all the traitors in Hong Kong, I really detest him the most. I first came across him in a BBC documentary in the early 90s when I was a young man. And I thought then, wow what a traitor! He's subsequent antics only reinforced my first assumption of him.
The next question is, can his "country" make demands for his "return"? (I'm still not certain if he is a British or Canadian)?
IMO, it maybe worthy of consideration if the whole judicial system's members free from anyone who is holding dual citizenships.
It is a requirement that in order to be a councillor, one is expected to give up foreign national citizenship. So why not judges?
However, it is probably more difficult to apply in practice. As we keep telling the one from the A-Team when he keeps saying it is the governments fault in appointing this foreign judges.
That's because of the very very small gene pool of judges available with the knowledge of the British judiciary systems. First and for most requirement is one needs to be a barrister. A barrister that has been trained and exposed to the British way of life. (Inevitably leasing to anti-China stance)!