VFX God is an appropriate term mainly because it was his performance that made motion capture from something interesting to something huge.
No doubt Serkis is an amazing actor but acting simply is not enough. Antony Hopkins a giant of acting and he was motion captured for Beowulf , not an actual film but a 3d animation film and still his acting looks fake and plain bad. And let me repeat his name again Antony freaking Hopkins.
So being god like actor is not enough. It’s clear from his reply that this guy is no animator, no 3d or 2d artist , no VFX editor but none the less he is the only one that had not 1, not 2 but 3 hugely popular performances
Lord of the rings
Planet of the apes
You cannot achieve that without an excellent knowledge of the behavior and limitations of technology. You cannot achieve that through acting alone. You have to be in perfect sync with the artists that will receive your performance and be able to handle issues beforehand . He pretty much put the last nail to the coffin of the argument that 3D cannot achieve true realism because animation was always the weakest link of 3d.
I am willing to bet he provided golden suggestion for the improvement of mocap software because we know that even when they use commercial products they still create additional tools and extensions to deal with the specific challenges of the film. So who is the best to ask for how to improve such software ? The dude with the 3 amazing performances is my safest bet.