I think this is unfair- to Ayn Rand. I used to be a bit of a Randroid myself, and I never got the impression from her writing that she hated the toiling masses, just thought them irrelevant. Her work very much hinges on the "great man" theory of history, only expanded out to basically everything. The Fountainhead is ultimately the battle between Rourke and Toohey, not Rourke and the obsolete mayonnaise ghouls who don't appreciate his greatness. They don't appreciate his greatness, but that's because of Toohey's influence, not because they're evil or even (necessarily) stupid.
As a philosophy, Objectivism really attracts people who are breaking or have broken from their roots; Rand herself was a Jew from Soviet Russia, but her homebrew philosophy rejects Judaism, Russian-ness, and Communism with vehemence. Religious apostates are common converts (Bosch Fawstin comes to mind) so it would make some sense that Bob, as a basic-bitch ex-Catholic, would have at least some attraction to the philosophy. But I'm generally inclined to believe that his petty malice towards anyone and everyone he considers inconvenient to him in some way is less a philosophical stance and more him just being an asshole. If you had to draw a fictional comparison, he'd be a fat, incel version of one of the main characters of Rope.