Nigegilb,
I am sorry but I cannot see your incident having any relevance to fitting of Mode S to the Nimrod Fleet.
Mode S is a civilian ATC IFF enhancement giving additional information and with the addition of some extra bits dovetails nicely with ADS-B.
The C-130 not transponding would not have any enhancement offered by Mode S if it ain't switched on and thus would not have been a factor in the tale you related.