The land ASAP is attached to some ECAMs. In this case, since there was no fire warning, I would guess it would have been linked to the fuel leak ECAM. It refers only to the ECAM to which it is linked. It does not take into account multiple failures. After takeoff, with the feed tanks fullish of fuel the fuel leak may not have been considered as concerning as the stopping problem of being in the highish 400t low 500t weight range, having over half the anti-skid inop, having no slats.
The LPC at that time had a problem doing landing calcs with some combinations of these failures. Hence the best guess result was a number only 100m less than the LDA. There is no page 4.03 in the QRH to help with these calcs. The only way of reducing the landing distance required in this case was to reduce landing weight.
Remember also Vapp was increased due to the no slats. This speed did not consider any lateral imbalance due to fuel leak.
Airbus might suggest landing within 60min of a red LAND ASAP, however it also has 180/240 ETOPS on its twins, I don't think they would expect you to ditch after an hour, but would rather prefer you did some pilot sh@t and risk manage. As I said the land ASAP is triggered by certain ECAMs by the Flight Warning Computers. It is no smarter than that.