I don't think that is correct. They'll need to generate and store hashes of all three variations on the plaintext password before discarding it. For example, given a password of "AaAaAa", where the user attempts to log in with "AAAAAA" (doh, capslock!), how would they guess which characters you intended to be uppercase and which not?
With capslock on the password would be entered as 'aAaAaA' (which would pass) not 'AAAAAA' (which would fail). There is no guessing, it is just the inverse.
Also, while caps lock + shift is still uppercased, caps lock has no effect on the non-alpha keys. Indeed on a Mac, caps-lock is not shift-lock, it's literally caps-lock: on my French layout, caps-lock'd & gives &, not 1. Since keys with diacritics and other marks like é è à ç adn ù are first-class keys on a french layout, they themselves are capitalized by caps-lock, and not giving in to the shift behavior (which would yield 2 7 0 9 and %). This allows to type É È À Ç and Ù without composition.
If you want the caps-lock-gives-numerics behavior you need to set your layout to "French — numerical" — its icon is a french flag with 123 at the bottom — instead of simply "French".
