But they made it for zombie games, and were specifically going for grotesque and creepy motions.

I don't see what this has to do with the disabled.

I think this is simply reflective off Miyazaki's view of what animations should be represented at all, and what entertainment in general reflect upon. He's not a fan of the grotesque, creepy, or disquieting.

If this is a group of his subordinates and they came to him with this.... they truly failed to capture the spirit of his animation style, and were way off target with their goals. Claiming it could be used for zombie's seems like a poor post-facto justification for their failure.