Short trip testing requirements

[ExtremeNeighbourhood36]

I'm a US citizen temporary resident/work permit holder flying back to the US for 48 hours. Having heard that for short trips like these you could get your pre-arrival PCR test before you left Canada, I noticed the government website seems to restrict this option to Canadians:

For short trips that are less than 72 hours, Canadian citizens, people registered under the Indian Act, permanent residents and protected persons travelling to the United States are allowed to do their pre-entry molecular test before they leave Canada.

This doesn't make sense to me seeing as the virus doesn't discriminate by citizenship, but I just wanted to confirm that I'm reading this correctly and I have to get a second test in the US before I return. I couldn't get a straight answer from the CBSA call centre (as usual).