There is kind of a difference though IMO. Re the double standards. I do actually try not to have double standards in general and I try to avoid sexism against men. But OTOH, group lusting over someone fanciable is something both sexes do, including all sexualities.
When men do it about a woman, I don't mind if it's respectful and not threatening. I wouldn't mind men saying to each other "Phwoar Laura Kuenssberg is hot and I totally would" (to keep with the Westminster theme :o).
The problem comes because there is a context where men are more powerful and in RL a woman is more likely to be in a situation where she doesn't have a choice / could be forced / attacked by men and we all know that, and some men's "lusting" tips over into that realm. So female group lusting, in this context, is generally less threatening.
That doesn't mean it's OK to do it to a man in his presence if he doesn't like it, make him feel uncomfortable etc. Neither way round is that OK.
But piling in saying "phwoar" about someone is normal and should be OK. It should be OK either way, and the more equal the sexes become, the more OK it is IMO.