I think aikido is not complete, but it is still great. It is not required to be complete to be great. How would you readers feel if your dojo brought in a kali expert once a week to show knife disarming training? Would you want that?
Is whatever Kali teaches about knife disarming that different from Aikido? Are there really any magical body movements that allow you to safely take a knife from a knife-wielding attacker?
Personally, I hope I am carrying a good, sturdy umbrella in that situation, or at least can grab some nearby object like a chair.
Failing all that, of course it is better having practised some movements than having practised nothing.
Fwiw, there was a nutcase here in Akihabara a few months ago who stabbed 17 people with a dagger on the street before being apprehended. The video shows that the cops kept him at by with sticks... nothing about fancy "disarmament" moves. (I suppose in countries like the US heŽd been perforated by a bullet.)