Except Google began using it immediately and did so for years before the patents were disclosed, and the w3c abandoned the standard prior to even asking about royalties. I think the w3c is at fault for the fracture in the standards more than anyone else. It's my understanding that Apple holds patents on the canvas standards that they do not require royalties for as well
Irrelevant. Did they give a promise not to do so? If not, using that API would be commercial suicide.