User blog comment:The King of the Monsters/24 Hours of Godzilla/@comment-11836-20160202200439/@comment-25285745-20160202201532

Well, according to Matt Frank (at least I think it was him, it might have been Chris Mowry), Toho did not want IDW to show Godzilla eating a whale in Rulers of Earth. Instead, IDW had to just show Godzilla stalking the whale and then get distracted by something else.

I think that ever since the Heisei series, Toho wants Godzilla to be portrayed solely as feeding on radiation, even though in the past he was canonically a carnivore.