Actually the TL;DR is even shorter: "I won't work on FPSs".
If you read it closely you'll see that he talks about someone who shielded his children from violent computer games, then he says that he'll never work a FPS again citing "ethical reasons", but never produces any kind of argument connecting these two points, or stating what those ethical reasons actually are.
I know it's just a blog post and all but I saw the length of the text and was therefore hoping for a more reasoned discussion rather than anonymous anecdote and soul-searching.
He seems rather hung up on "protecting children" from something, although what outcome he is afraid of is entirely unstated. I was not shielded from the horrors of the world as a child so it is unclear to me what has changed in the last twenty years, or what makes, specifically, the first-person-shooter genre such a travesty in his eyes.