I am not sure on this because I think I have stumbled upon some ICO and cryptocurrency-related ads in Google just days ago. I am not sure though whether it is directly in Google or some through sites which I browsed through Google. But I think it is very much possible that Google did not really fully ban ICO and crytpocurrency-related ads. Just like Twitter. Until now, I can see a lot of ICOs being promoted through twitter. And even Facebook.