Rush is always crass (and that is being generous).
The issue here is that he worded his comment as a personal attack on the woman’s character. He could have made his point instead by speaking in generic terms (applied to no one in particular) and been no worse than usual.
In response to your complaint, what is wrong with the call to boycott? It is an extremely democratic response to something you don’t like. I might even say it is epitomic of democracy, because you are inviting every individual to vote on the boycott with their money.