It has nothing to do with fairness. It’s that his political opponents are very, very afraid of him.
Bingo!
More succinctly, given our lst Amendment it is treacherous for a government to do nothing about such banning from public structure when based on political viewpoints. It is on a par with standing by idly when individuals are banned from public spaces based on being of a specific race. Here it is hypocritical; just a few years ago the libs were clamoring for equal viewpoints on conservative radio shows.