For comparison: you can bring your own DOCSIS modem to a cable network, even though all the houses on the street are connected to the same cable and you could jam it, or send a voltage spike to break everyone's modem.
They do however have the right to mandate certain configuration parameters just how they are allowed to mandate you connect something that isn't a noise generator to e.g. a cable TV outlet. Well, being able to limit you to connect devices that conform to some spec.