Microsoft would at least like him not to do that job for a competitor.
Given they paid for a big stake in the market leader, and their stock price movements when this drama erupted, keeping these people in-house can be seen as damage control.
>>anonym+(OP)
Sure. But Sam Altman is an ambitious man. Why would he accept this instead of fundraising and creating another company? I think there would be more details of this arrangement surfacing these coming days. It is unlikely a traditional team within a large corporation.