It's not a legal precedent, it's an interpretation of a law that they are mandated to enforce.

the case from the fishermen currently in Supreme Court, precisely will nullify unelected agency officials from interpreting laws like this to legislate, then enforce, rules outside of the mandates and powers granted by the populace

how can the FCC enforce laws?

ITG Tracebacks https://tracebacks.org/

With enough evidence, operators are compelled to provide data and are given an opportunity to correct their action. If they refuse, FCC will eventually issue an order to all other providers to not accept calls from the bad actor.