I agree with you that personal responsibility matters and that the students bear a heavy share of the blame.
But the "nobody forced students to attend" argument doesn't absolve the institution of blame. They created an attractive nuisance, and cynically, in my opinion. They knew they were in a no-win situation, so they came up with a crafty move: instead of proactively switching to online-only and costing themselves millions of dollars while catching a ton of flak for closing up, they invited the students to be the scapegoat, knowing they'd screw up and would take the PR hit for forcing the school's hand to close.
That's all well and good, and it is the students fault for proving everyone right, but it's not an ethical choice by the institution; they've got a responsibility to create a safe atmosphere for students, faculty/staff, and the broader community. They punted on that.