Net neutrality would have made this kind of action illegal. ISPs are not publishers, they should be routing all legal traffic.
There isn't enough information on either the linked site or the https://protectthestack.org/ site they link to for more information to tell, but as with enforced DoH in the browser I'm afraid this is a lot of high-minded nannying that just so happens to align perfectly with big tech's interest in protecting their ad networks from DNS filtering.
Maybe I'm paranoid, but I feel there have been a lot of simultaneous efforts to wrest control of my networks and devices from my hands ramping up over the last few years.