I just noticed that PHAC has released some useful data as of May 28. The positivity rate for airport-tested arrivals plummeted to 0.4% in May (since the India travel ban). Right in line with my speculative math from a couple of days ago.

One of the justifications for not having the hotel quarantine at the land border was the very low positivity rate there (0.3%). These new numbers could provide a reason for the Feds to start phasing it out and a chance to save face by claiming it's data/science based.