Protester shot in chest by live police round during Hong Kong protests

> Imagine if the US suddenly had a dictator

This is why we have the second amendment. And the constitution as the thing to which office-holders swear allegiance to rather than to "the party" or "the president".

If HK'ers had a similar right to carry guns, do you honestly believe that they would be any better off right now?

It’s uncertain what the eventual outcome would be, but one thing is for sure, it would increase the threshold before the tanks rolled in.

I might be misreading what "increase the threshold" means, but it seems to me that if people were armed, the tanks were more likely to roll in quickly, not less.

No, he's correct, and it means exactly the opposite. The armed citizen is a deterrent to rolling tanks at all.