There are open standards for browsers to communicate with software deployed in web 3, regardless of what an isp would care about doing. For an ISP to fiddle with that goes far beyond sneaking around net neutrality as a principle. It would entail blatant violations of existing laws. In broad daylight.
Not to mention it would accelerate the adoption of Starlink and other alternatives, as well as community-deployed mesh networks that are already covering cities in the United States of America as we speak. And this hardware will get cheaper and better with time and be deployed at larger and larger scales.