By converting this outlet into a junction box (presumably by removing the GFCI and splicing the line and load cables together), the homeowner may have eliminated GFCI protection elsewhere, such as outdoor receptacles, or even in the bathroom/kitchen.
Back when GFCIs were new (and expensive), it was somewhat common to install one unit in a basement or garage, and then use the load side to feed all the other GFCI-required circuits in the house.
I would suggest a check of outdoor recepts and bathroom/kitchen circuits to verify that they still have GFCI protection provided somewhere...
