That is what I thought. The same as in a 757 or many other models, however this bottom-of-the-reservoir way of protecting against a leak needs piping of its own to and from the users, right? and these users are typically few and emergency related, such as alternate brakes or similar.
I mean, it cannot just keep serving all the users. The fluid would go out through "the hole" in no time, right?
Definitely there is very little information about this in the FCOM, and I don't have the AMM...