Can one of you lawyer type people explain the Hooters BBQWTF thing (maybe in relation to this)?
I don't think that's ever been litigated - someone correct me if I'm wrong. Many men have sued Hooters over the last 20-25 years claiming that they couldn't get hired as servers, and Hooters always defended with the BFOQ ("bona fide occupational qualification") assertion, the same general rule that enables, say, airlines to have an age maximum for pilots in some (not all) cases. However, I think every single one of those cases settled out of court.
This SCOTUS decision is pretty narrow and actually leaves the "undue hardship" and BFOQ questions for remand to the trial court, because what SCOTUS did here was to reverse the Tenth Circuit's grant of summary judgment in favor of AF, which ended the case in AF's favor. All the SCOTUS decision really says is that knowledge of an applicant's religion in a failure-to-accomodate case is not required, because the statute doesn't require that the employer know anything.
This is one of those weird decisions where some of the righties on the Court defer to a "religious" (pun intended) reading of a statute because it gives them cover for other, similar decisions. Scalia loves his literalism, and here's an exhibit that supports that.
Basically, when you have three opinions on an employment matter, all written by the Court's three most conservative members, you know the case wasn't litigated or decided well in the courts below.
TL; DR: Hooters cases are different and the central issue there wasn't part of this appeal. All this SCOTUS decision says is that the failed applicant isn't required to show that the employer knew about the applicant's religion in order for the failed applicant to establish intentional discrimination.