The only reasons I can think of: A. Core team members leaving (perhaps more threatening to leave). B. (maybe more likely) Nadella told Sutskever that he might

The only reasons I can think of: A. Core team members leaving (perhaps more threatening to leave). B. (maybe more likely) Nadella told Sutskever that he might shut off funding or restrict compute resources if he didn't reverse course, or at least, wasn't able to retain talent (see A).