If you have worked in a sufficiently big org this would have been normal to you. Executive assistants send mail which purports to come from the executive himself. That is the kinda thing which happened here.
so do you have some kind of inside knowledge about what happened? if so can you give more details about how exactly she improperly used an executive's email? what did she send and to whom, i wonder. and if you don't have any inside information, could you reflect on what motivates you to defend openai here?