The present rules in Canada are that there are only four "airports of entry" , of which Vancouver is one. There is no provision to land and make a fuel purchase in Canada without clearing inbound customs. Customs officers do not provide a "supervision of non clearing pilots" service. You either clear in, or you don't enter. Right now, clearing in would require a formal stop at Vancouver. The Canada/US border has effectively been closed to all but a select few "official" purposes for just about a year now. This has been inconvenient, but clear. Presuming that this pilot properly filed his flight plan for a Canada overflight (which is probably fine, though I have not checked that for myself), he would have understood the requirements and limitations for clearing Canadian customs, even if just for a fuel stop.
As a Canadian citizen, I once arrived back into Canada, and presented myself to customs, without having filed a flight plan. I was in major trouble for landing in Canada from the US without having filed a flight plan. Neither customs authority take this lightly.... Indeed, [apparently] if I arrive to US customs more than 15 minutes either side of my flight planned arrival time, there's big trouble, though I have never tested this. The rules are well published, and have to be followed....