Due to no flights i guess there's been no one who travelled as a student
plus courses are either deferred to fall or online so there seems no valid reason to travel to Canada and most of flights which are there amid lockdown are specially for PR or citizens and we don't fall in this category.
[Feel free to correct me here i guess IRCC make this restrictions exemption but it depends on CBSA to control this exemptions . if they want to allow someone to enter Canada or not and they will argue if someone student visa holder before 18 march about their entry because they know about defer and online course]
Maybe international flights starts in june that means we can travel in july or august worryfree...