Apply view contextual filter only if user role is not administrator
Not entirely an answer to the question, more a workaround, but you could do it as follows.

Make sure to create a second page. It has to be identical to the original one (including the path), so you can clone it from the edit view name/description dropdown button. Then make sure to remove the contextual filter from this display only, and limit the access to users with the administrator role. Finally make sure this views page is listed before the other one (reorder displays in the edit view name/description dropdown button).

This works because views attempts to load the path, if there is no access for the first display, views attempts to load the second display. 
So all users that have no administrator role will see the second display, while the admins will get the first display without contextual filter.