Hmm...
Well regardless of what I think of the no-zero policy at that school district, the article states that it made that change more than a year ago. The teacher who was suspended clearly and simply chose not to follow that policy. Suspension may be a bit harsh, especially in the middle of the class term (as one student was quoted as saying), but some form of punishment is likely necessary. Otherwise any teacher could ignore any policy.
Like the ATA is quoted as saying in that article.. "The ATA believes teachers should primarily be responsible for assessing and evaluating students, ATA spokesman Jonathan Teghtmeyer said. However, teachers are ultimately accountable to their employer, he said."
As a further thought, there was probably a better way for a teacher with a 30+ year career at the school to fight the policy than to outright ignore it.