I still think you misunderstand what the text states.
The link states that as long as someone qualifies for essential travel an international student can come to Canada if
A) he has a study permit already (not a first timer)
OR
B) his study permit was approved before March 18
OR
C) he comes from the US (including any foreign national)
The big question is what it means (come from US). Geographically from US meaning it is regardless of whether that person lived in US or just came to the US and makes his way through the US to Canada.
yes you can enter canada as long as you satisfy at least 2 requirements:
1. a proof your program of study is essential/non-discretionary
2. approved study permit or (before March18)
and of course don't forget to provide them your 14-day quarantine plans or place to stay
just show to Border Services your documents if ask...if not they will stamp your passport (",)
check also other threads, some students already able to enter canada not coming from US