But couldn't that alternatively be explained by the cerebral cortex being able to act as a "backup" of sorts for the cerebellum, to the extent of "neglecting" its ordinary tasks? It would make sense if the brain were to "consider" motor control to be at a higher priority than cognition, and was designed as such. (Sort of like in a pinch a kitchen might use a cook as a dishwasher.)
I'm using wishy-washy words here, sorry. I don't know how better to explain it.