Two other factors important to note:
1. Panic isn't necessarily an unreasonable response in an achievement-oriented student. The majority of teachers at the school use the "temporary" zero as a close precursor to the PERMANENT one... and the timeline on conversion is highly variable (could be 24 hours, even, or maybe never-- you don't know WHAT it means unless the teacher says so).
2. Students can't actually "use" the gradebook as a means of immediate feedback on course performance (the stated intended purpose of making it available to students in the first place) because that information's obscured as long as there are temporary zeros in place... and this teacher is notorious for ZEROING OUT THE ENTIRE COURSE-- (in advance) that is, you won't know how you did until you complete the final, unless you're willing to painstakingly calculate it yourself, I mean... and assuming that the weighting isn't shifting under you because of invalidated items on assessments (which happens-- honestly, that gradebook IS the only way to know-- I know, because I've tried doing it the other way in the past... there is some bit of weighting info that is not available to parents/students.
So yes-- I do believe that this practice is a GROSS escalation of communication and should be used more judiciously and never without communication to parents.
Some students are required to submit weekly progress reports to play club athletics here. Some may have parents who immediately resort to fairly punitive measures for any grade which is less than __________. Frankly, in my own home as a child, this would have led directly to ABUSE. Any explanation from ME would have been "excuses" which would be worthy of additional verbal/physical "punishment." My grades HAD to be acceptable or it would set one of my parents off, in a big way. Anyone else live in fear of the "call home" or the "note from the teacher" about a classroom infraction as a child? No? Well, welcome to life in a home with an abusive parent-- the ONLY good news from school is news that is bland and doesn't make waves. These teachers have ZERO way to know who those kids are by virtue of the environment (virtual), but statistically, they are out there in the same virtual classes that my DD is in.
So I have grave concerns that don't involve my OWN child at all.
