It is a good point you raise Sandy,
Yes indeed there are so many variations in anatomy.
I have the privilege of conducting four cadaver workshops each year and you start to wonder if there is actually a person who is built according to classic anatomical guidelines.
There are so many variations.
In this case I would use the logic that a Baxters neuropathy that effects all of the plantar intrinsic muscles should be unilateral in nature and also other muscles like the extensor digitorum brevis on the dorsum of the foot and the calf muscles should be spared from the process.
Also the lack of a diabetes history would strengthen the case that it is an isolated neural failure.
Steve