Heresy is a verfiable accusation. It's a word that has an actual religious or theological connotation. "Whoring" is being employed as imagery of societal pondscum (as it were) to personify our holy mother Church. Given the context of the "Whore of Babylon", Topcat is calling us in league with Satan. If Topcat needs a Thesaurus, there are plenty of online resources. Using the word "whore" is intellectually lazy and designed to shock, not make efficacious.
I see. What you and others say about so-called "Protestantism" is true, so it can't be nasty. What topcat said is untrue, so it's nasty. Are you kidding me? Would you like to be called a heretic? Would you like to be told you're not a Christian? If you don't think that's offensive, we're not on the same planet.
Malachy uses the imagery of the whore of Babylon on 7 hills. John called it in Rev 17, "the city that rules over the kings of the earth."
In John's day that was Rome.