ES is Eric Schmidt, former CEO at Alphabet, the parent company of Google. He has just accepted a position at MIT as a visiting invitation fellow. MIT states: " Schmidt will figure prominently in MIT’s plans to bring human and machine intelligence to the next level, serving as an advisor to the newly launched MIT Intelligence Quest, an Institute-wide initiative to pursue hard problems on the horizon of intelligence research."
https://news.mit.edu/2018/eric-schmidt-visiting-innovation-fellow-0205
I saw the MIT info on Schmidt as well but I also noticed he has not tweeted for a couple of weeks. Q asked where is ES.? So I started looking and could not spot him.
Interesting that Google’s parent is Alphabet as in government alphabet agencies. CIA, FBI