There is no evidence that Nabisco was offended. Perhaps the just didn't want any illegal likeness of their products to be used. For all we know. Milton Bradley has no idea about choperation, perhaps they do know and don't care, perhaps they do know and they like the free advertising. Company motives is purely speculation.
It was mentioned in one of the reference books that Topps returned to Nabisco products with Bum Bums in Series 6, which suggests maybe there never was a C&D request on Ratz/Cracked, or maybe they were just willing to take a gamble on a new parody after some 7 years had passed between the 1967 Die-Cuts and 1974 Series 6.
In the early stages of the ANS era, I had questioned whether maybe Topps had done some legal maneuvering to eliminate The C&D problem, maybe even something that could have taken years to get through the courts. No one knew the answer to that, but there is no evidence of modern-day Wackies being hampered by C&D issues in any way. Maybe corporate attitudes have changed, believing that any attention, good or bad, to their products is better than none.