I have found a patch in these forums that fixes Pip grid glitch, but do we have any such Pip specialist here who would know how to completely stop Pip evolution mechanic. I think I could do it by editing every battlescripts but that would be quite unoptimal way if it can be done by simply zeroing some data somewhere else.
EDIT: Simple solution: Give the normal Pip the model of the fully evolved Pip bc model 2B, 2C or 2D is always a condition for the evolution to happen. This solution also allows the use of Pip's techs that require wings to look sensisble. Problem solved.