Purely speculation on my part, but that makes a lot of sense. During the Ballmer era, he would have wanted to send a clear and unambiguous signal that he was no longer calling the shots, so he would have made a greater effort to step away. Also important was that, while Ballmer wasn’t technically a cofounder, he had been around since the early days. With Ballmer gone and Gates having demonstrated that his foundation is by far his #1 focus, there’s less reason for him to give Microsoft some distance and more reason for him to occasionally show up and, among other things, serve as a living connection to their early history.

He probably got involved again because Ballmer made such a big hash of things.

> There is some surprise that Gates seems to be more involved in the Nadella era

Nadella had asked Gates to step up and be more involved when he accepted CEO position