True, but you haven't sodablasted the hull, so the damage might actually be centered around the two fastener holes.... What is immediately visible is the shape of the block. Also, if the outer layer is matte, which is usually the case, the different directions could be due to the water wicking along the CSM strands.
I have cleaned paint off around the area and verified that gelcoat is in just as good a condition as elsewhere immediately outside the ground plate area. It really is a perfect straight line demarcating the damage and the good gelcoat.
That the wicking in outer layer would just happen to match the shape of the plate is possible, of course, but sounds somewhat unlikely.