If the NTSB licensed trucks, and there was only enough road space to license 100 trucks per city, I'd be perfectly fine if they decided that 50/100 trucks had to be locally owned.
Usable radio frequencies are a limited resource, we have a vested interest in allocating those resources efficiently and fairly. The argument is what constitutes efficiently and fairly.
Is it fair to award licenses to the highest bidder? How about the tallest station owner?
Regardless of how they allocate licenses, they are still making a choice that determines who gets access and what viewpoints are represented.
I see no intrinsic reason that "highest bidder" is any more fair than "lives within 100 miles of the radio station."
The fact that getting rid of hose regulations might help any particular group is besides the point. To the extent that those regulations were based on an attempt to influence viewpoints, they were not legitimate to begin with.
In the same way consolidation among trucking companies is outside the NTSB's jurisdition. The FCC's legitimate purpose is to prevent interference among radio and TV stations. It's not to regulate content (which isn't a legitimate area of regulation at all). And it's not to enforce antitrust laws (which are enforced by a different government agency, with specific expertise in antitrust).
The fact that radio is influential in politics among a certain segment of the population is even more reason for the FCC to steer clear, not a reason for the FCC to intervene.