I, as a user with 10k+ karma on HN, can testify that the author has all the hallmarks of a real blind person (active in blind communities and so on). I don't have any evidence suggesting that the author ever engaged in deceptive behavior.
In other words, my P(real) > 0.99.
Sure. He's real. ̶̶̶ ̶T̶h̶e̶ ̶s̶t̶o̶r̶y̶ ̶t̶h̶o̶u̶g̶h̶:̶ "Robert Kingett is a Blind, and gay, obscure writer. He writes fiction where Disabled heroes get their happy ending..."
Edit: Yep, appears I have it wrong. Thanks for the pointers. The non-fiction tag missed my eye.