This is not censorship and neither was it censorship when MediaMatters convinced some not to advertise on Rush. IIRC, only governments can engage in censorship.
It’s business and the perception of the public.
Boycotts and embargos are private actions implicitly authorized, even encouraged by the 1st, 9th, 10th amendments.
A city council in California tried to extend the Media Matters “boycott” to prohibiting stations in the community from broadcasting such programming. Additionally, there were calls to the FCC to ban Rush so there were attempts in censorship in that case.
Government restriction of speech is censorship. And it was politically based, not because of the word “slut” being used.