Leaked memo? Who made that claim? It's posted on Microsoft's own website.
Carefully crafted? Uh, yeah, it's a resignation letter from a major corporate executive that is publicly posted. Should it have some LOLs and emojis?
To reiterate the point without the confusion regarding 'leaked': The media is the message. The form of the news/announcement of the resignation came in shape of a memoized email exchange, as if these actual words between Ballmer and Satya were exchanged in this actual format.
I submit that they were not.
I submit that the substantial majority of the content was not written by or for Satya nor by or for Ballmer, but that this announcement is for employees and investors to read. I submit that it is also a method for Microsoft to contextualize a complicated decision for the tech media and for the digestion of the broader interested public.