Yes. California is definitely going to argue the FCC had no authority to reinterpret things when there is zero changed evidence/etc. It is definitely "arbitrary" (whether it meets the legal definition or not)
At least one trump agency that took a hard right turn has already lost in court on that point in the past few months.
The case escapes me, but it was in fact "the evidence has not changed, you can't just decide you don't like what was done before for political reasons".
FWIW: I suspect the real argument here is that congress has preempted California.
IE they could regulate this space, and have chosen explicitly not to do so, through the '96 act, etc.
It's a little bit of a weird argument though, because it's saying "we explicitly didn't give the FCC authority because we didn't want anyone to regulate it", even though the FCC has in fact tried to regulate it in the past because they thought they had authority :)
(IE Congress's intent was not so clear that we didn't have years of regulation, etc)
