Content filtering is by no means critical and shouldn't be used at all. All it does is punish students who don't know how to use Tor. Every school I've been to besides my highschool had either no filter or a DNS or HTTPS based filter, and most students used VPN apps which are likely worse for them (spyware etc.) than not having filtering. My highschool used Fortinet which also did SNI blocking and tried to block Tor, requesting new bridges allowed me to connect. At least Fortinet quickly reclassifies false positives though.