maybe that's not the only reason john mcafee to stop promoting ico because it's risking his reputation
What reputation? His reputation as a scammer and con-artist?
Before there were too many crypto enthusiasts that are looking up to him but with his past actions of being a shill, only few believes him now.
There's no reputation that he is longer protecting, it's totally destroyed although there's still hope for him if his prediction about $1,000,000 will happen but no one's believing him with that.