Right. No evidence it's neurological? What else can it be? Spiders are not fully in control of their movements. Motor function is controlled by the brain. is it by definition neurological. Even if it is not neurological it IS non-normal behaviour for a ball python. Other morphs do not cause non normal behavior. That is why I don't like it.
Musculoskeletal, possibly. It does look neurological, but it would be interesting to know for sure.