Mongoose has sort of moved in that direction already in regards to using the Athletics Skill. Athletics (Dex) is generally a better reflection of acrobatic ability than raw Dex, and isn't used for manipulation style Dex tasks.
However, they are LARGE creatures. Yes, "descended from pouncers", but neither are they housecats or leopards. Generally, bigger means less ability to change direction rapidly; Aslan do alright in that regards, but they seem to be designed for that rapid burst of straight line speed culminating in teeth and claws in prey. Melee (Natural) is the skill and STR is the stat.
The original stat division (one of a handful of things inherited from D&D) which is largely retained in Mongoose, is Strength for hitting, Dex for shooting. Mongoose does allow for Dex to be used for attacking in melee, but Aslan are in no way disadvantaged here. Quite the opposite.
If Aslan were arboreal pouncers, or much smaller, no Dex penalty would make more sense.
From a game balance point of view, it works. They're the bruiser aliens to the Vargr's finesse ones.