Does Starlink in Canada use US Ground Stations? I suppose someone could register them just south of the border and smuggle one in. But Starlink tends to follow all laws in every jurisdiction they operate in, and registers as a carrier entity there. I doubt Starlink would refuse any legal obligations that risk losing access to a region.
I doubt Starlink can somehow bypass Canadian law. It's the countries who rule and enforce the EM spectrum usage on their land, and countries are prepared to go to great extents in enforcing whatever rule they come up with.
What forms of digital identity could be used to enforce an internet kill switch / blockade for specific humans?