Where does it state that even in normal times Americans can apply for a study permit right at the border without any prior approval at all? Then at least there is something to start with. Applying at the border is one thing (and I made no claim about that but am curious to learn more) and entering without approval is another.
I am also looking for a link - I had an immigration lawyer tell me today that POE applicants from the US have been successful, but it’s still up to the officer and therefore risky. Unfortunately I can’t find anything online about it - but as hjkojima mentioned, it’s probably kept on the down low.