Looks like he did it on purpose. I'm gonna copy the comment here in case he decides to delete it.

I shut down the sub because I regret making it. It's a place that though, it had noble intentions, was entirely about bad talking a show and its creators. I feel that this sub shouldn't exist anymore because the creators and those affiliated with Game Grumps don't deserve it. They created a popular show, and though they don't deserve having a special place reserved for people complaining about them. Every YouTuber has a rule of "Don't read the comments". They always talk about how the comments sometimes ruin their day and make them feel like shit. Nobody deserves that. It's like there's always that question. If you had a book of everything anyone has said bad about you, would you read it? The Game Grumps don't deserve a living, breathing community doing just that for them, they have their own things to worry about. /r/VentGrumps had started rough, gotten better, but went right back down the old path. It became vitriolic and hypocritical, having positive vents but in the same breath demeaning the members of Game Grumps. I formally apologize to Arin Hanson and the rest of the Grumps for my sub and however it may have affected you large or small, and I urge the moderators of Reddit to not allow subs like this because they promote bullying of others and I take full responsibility for my sub so I decided to end it to stem the tide of negativity.

Also those criticizing me and calling me a douchebag for leaving the sub like that, it was the only way I wanted it to go. I guess I could have explained, but what's the Grump community without any drama? ;) I'm out, kids. You may see me around, you may not. I haven't decided yet.