This is what it says on the Canadian website:-
If you’re an international student who has a valid study permit, or were approved for a study permit on or before March 18, 2020, you’re exempt from the travel restrictions.
I feel it shouldn't be an issue for you to enter Canada if you satisfy the above condition.
Exempt doesn't mean you can enter. What you quoted only a part of it. This is what CBSA is asking:
Arriving from the United States
If you are a foreign national arriving from the United States, to enter Canada, you must prove to the CBSA that you:
- are travelling for a non-discretionary (essential) purpose or are only transiting or are an immediate family member
- are not presenting signs or symptoms of COVID-19
- have a plan to quarantine for 14 days, unless exempted
These measures are currently in effect until July 21, 2020, and may be extended.
Arriving from a country other than the United States
If you are a foreign national arriving from a country other than the United States, to enter Canada, you must prove to the CBSA that you:
- are listed as being exempted from travel restrictions (including immediate family members)
- are travelling for a non-discretionary (essential) purpose
- are not presenting signs or symptoms of COVID-19
- have a plan to quarantine for 14 days, unless exempted
These measures are currently in effect until June 30, 2020, and may be extended.
Basically, if I arrive from a country other than the US, I have to prove my travel is essential AND I'm exempt from the travel restrictions. If I arrive from the US, which is my case, I have to prove that my travel is essential. Currently, it's still in discussion what would be considered as "essential" It really depends on the CBSA if they consider a travel is essential or not. It's subjective for sure.
Since I'm staying in the US under a F1 visa and on OPT, I'm just afraid that if I'm being denied entry by CBSA, what will happen to me since my country is closing border and I can't travel back to me US as my visa expired. I don't know if automatic validation will work during this time, but it's risky for sure