Is there a good reason why he isn't the intense focus of technology dedicated to reading brain signals to action results through a computer + display? There ar

Is there a good reason why he isn't the intense focus of technology dedicated to reading brain signals to action results through a computer + display? There are already functional systems that paralyzed people have used to communicate through on-screen selections in that manner. Surely Stephen Hawking can acquire the technology and afford the upkeep. Hell, surely MIT or someone out there would build a custom rig for him and focus on constantly improving it to get more productivity out of his marvelous brain while he's still here.