Plus if he's sane that just means he could go crazy again!!! But I think Vincent can disarm the hwole 'hey your mom is an alien' thing when.. that dude knows his mom. directly in person.

Killed a whole town. killed tifa but not. tried to drop a meteor on a planet. he went off the rails!! it's easy to tell what earns him this weird monster purgatory but what did zack do to deserve it!