I work at microsoft and honestly the Mitchel guy seems unhinged. I saw him posting every 15 minutes on our internal Yammer today about this. He ranted a lot about how people at HR plotted against him in the past. Honestly his autism might get him fired because he took it way too far.
I'm not sure what is more cringeworthy, the email itself or the fact that this became controversial enough to warrant a response from Microsoft [1]. People on the Internet will express discontent over anything and everything.
might go without saying, but: do NOT get sloshed at events like this, even if you see other people doing it. you're trying to get a job, so keep your wits about you.