The TFU and also TFU 32.51.12.004 have referenced changes to FCOM/SOP 3.03.07 with Temp Revision 746/846 for pushback procedures, asking for the NWS/Antiskid to be selected off prior to pushback.
There was then an SB/Mod for the box 5GC for improved sealing, and then this TR for the FCOM/SOPs was removed.
Which is what the OP was asking about I believe, what were the advantages of having this SOP to have the NWS/Antiskid selected off for pushback.
So as BazB pointed out, due to the issue of 5GC failing to provide the BSCU with the ground that informs it the tow-pin is inserted, the advantage is, that if 5GC doesn't provide the signal, having the NWS/Antiskid switch in the off position will stop the nosewheels trying to centre (and breaking towbar shear pins), as the hydraulic pressure rises during engine start & pushback.
If the 5GC microwitch fails, it doesn't "fail safe" to anything, it will be simply a pushback as if the tow-pin was never inserted in the first place!
