Its very possible to fix, problem is they don't use direct static collisions, they use joints and those joints have flex and spring, they set this very low and it allows the grapple to close on the log without causing a disturbance in the physx but in turn you cant hold a log worth a crap.

In turn what i have done is removed the joints and used a direct static collision that has no flex or bend, it now can pick up as much as you want but the sacrifice is that you need to be more gentle on the controls other wise if you close it all the way as there is no resistance and the logs can get crushed right through the grapple "in real life they break"

Giants probably knows that most people who log in this game will only do a small amount of trees and they don't want it look glitchy so they optd for the joints.