User blog comment:SpaceManiac888/Rusty Spanner of the Episode: Series 10, Heat 5/@comment-6279140-20171127121430/@comment-2118191-20171127181443

The rules have stated, quite a few times, that a robot is no longer automatically classed as immobile if it loses drive to one side, but it IS classed as immobile if it can't move outside its own circumference. Toast will back me up here I'm sure, but from what I saw, Push To Exit fell into that definition - hence, out.