You are being used. Why did Ebert do a follow up post, after getting bashed by thousands of game fans? Because he got bashed by thousands of game fans. He’s in the entertainment industry and he found a way to touch a large audience. Discussing him just gives him a platform.
He is irrelevant, and his kind will disappear in not a long amount of time.
Don’t play along. You’re being used.
Who's being used, exactly? I'm fairly certain that people are going to know who Roger Ebert is, even without the links from the gaming blogs. But I'm even more sure that there are plenty of movie fans who are following the blog/twitter account of the most popular film critic in America, who would've never seen Santiago's video otherwise. Or heard about games like Flower and Shadow of the Colossus. Or even have been aware that there are people who care about art in videogames.

Anyone who's looking to change Ebert's mind is going to be disappointed. And anyone who's looking for consensus is going to be disappointed, too. And Ebert's savvy enough to understand that: he's been linking to the discussion about the topic, but never to people that agree with him. I think he's completely wrong here, but he's not stupid, and I think he understands that the discussion is more important than consensus.