GFCIs are required by the NEC in the workshop/storage area of this basement, no matter how much finishing you do. The theory of equivalent risk has to do with both the intended use of the space and its state of construction (finish).
That said, what is the real risk of non-GFCI outlets in this finished space? Is it any less or any more than the same workshop in the garage or upstairs in a converted bedroom? The AHJ needs to decide in these cases, because so much of the code is open to intrepretation of intent. Article 90.4 allows for this.
