In short, the Administrative Procedure Act. It sets out the procedures that have to be followed before policy decisions get made. If the FCC doesn't follow the APA's procedures exactly, that gives the industry grounds to sue. Even if the industry eventually looses, it would still mean a stay on the new policies during which they would continue to exploit consumers.

The APA isn't a bad thing, since it forces federal agencies to be deliberate in making policy decisions that could have far reaching consequences. That said, it does make the government even slower to react to situations that often change quickly. But it has tripped up this administration and previous administrations when they have tried to make hasty decisions, including Trump with his "Muslim ban".