WordPress is very accessible for screen reader users. I've been using it since 1.5 and have used it with Jaws including the latest version, Window Eyes, NVDA and VoiceOver. Your friend will do all of his management through the dashboard. It will help if he is very familiar with whichever screen reader he is using, because tabbing through the dashboard isn't the quickest way to get things done. I would also encourage your friend to come and post in the forums when he encounters things he needs help with. If he wants he can tag me with @arush so I will see it and can respond directly to him. It's not that I want to set myself up as the expert, but I'm definitely willing to help new users become comfortable with WordPress, especially screen reader users.