aog, others have explained to you when and in what context this image, or any image is , or would be, racially offensive. Do you agree with them? If not , why and how is your experience and knowledge of racism better than theirs? It may be that you don't, or didn't, understand why making monkey noises at a black footballer, or calling him a monkey, during a game, is offensive as racist.What is your present understanding of that? On reading past replies you may see why replacing Cameron's image with Obama's image in the cartoon would not be offensive. If you think it would be, what are your grounds for that opinion ?
Your conjecture to me is that there would be outbursts if that were done. If your conjecture is correct, the outbursts would be from those who did not know the reference to the three wise monkeys, would it not? They would be in error through ignorance. What answer is it to the statement that it would not be offensive, to say that those conjectured people would create outbursts? Or do you define 'offensive' as 'tending to offend ther ignorant' ?