The only heter to learn about other religions is if you’re a talmid chochom and it’s being done bederech “da ma shetashuv’, can you bring a source aside from a verbal declaration from an unnamed rabbi that for parnosa it’s allowed or that it depends on the person in such a case?
I think the crowd was shocked because it’s not what the gemara and rishonim say.
That issue is not so related to movies and other unnecessary influences; i will agree that there is a vast difference between someone who is forced to learn treif in order to finish school vs someone who carelessly entrusts his neshoma to goyishe directors for the sake of enjoyment