So the final chapter on the employee who couldn't do anything is we had a meeting scheduled for 2p Thursday. Instead, he dropped off a resignation letter with a secretary, another copy with a different admin, but not me, and walked out. He wrote a full page resignation about how he cannot work for me, then included 5 pages of Google Chat transcripts to cite examples about how I had wronged him, trying to rebuttal my memo.
Of course, his examples were cherry-picked and self-defeating (ex. He included a photo of a patch panel and his text saying there are two ports with the same room number listed; I told him I didn't know which was which and separately suggested he could check the status of the switch port and shut/no shut if one was disabled - for which I had provided step by step directions the month before).
So I got with my boss, who was also going to be in the meeting, and asked if he saw the resignation letter. He said, "I flipped through it but I don't give a shit about any of that. You and I handled the meeting well and he knew he ****ed up. It's the worst part of the job but sometimes it needs to be done, and we were going to end up here anyway."
Of course, he might have just screwed himself out of his state retirement by doing what he did. I really tried to be compassionate and humane, despite all of his shortcomings, but like everything else he did while working for me, he resigned in the stupidest way possible.