No, Obama didn't Tweet that.
One of his 20 hip and trendy young aides who work in the Office of Digital Strategy did.
Sure, the president is a superficially busy guy (fundraisers, press conferences, photo ops, more fundraisers, shaking hands with heads of state, doing what he's told, fundraisers), but... his Twitter account, something that is supposed to be so simple it's 140 characters or less, takes not just one dedicated employee, but a whole team of them.
That's right. We are to the point in modern society where the President of the United States has a team of nearly two dozen people whose sole job is to ghost posts to his official Twitter, Facebook, Instagram, and YouTube accounts.