Was the death of Gwen Stacy nationally broadcast? I don't recall that.
IIRC it's been retconned at one point to say that Norman was a genius and the Goblin formula only increased that.
Well, we still have peopl;e protesting Norman, just like how the majority of the country ignores teh protesters in our world, the same could be true for Marvel world. Plus, he does have the Cabal in his pocket as back scense help if I recall.