At no point did the government provide free N95 masks to school populations. You’re suggesting that providing them to some schools but not all of them in a systematic study to quantify the amount of benefit they provide over cloth masks would be profoundly unethical and that providing nothing (which is exactly what happened) is the better option? Hard disagree.
Early in the pandemic there’s no way that the government could have wrangled enough masks to provide free N95s for all students due to scarcity. But getting enough of them out there to generate good data was a realistic option that they chose not to pursue.