Anonymous C joined in and replied with this 5 days ago, 56 minutes later, 5 hours after the original post[^][v]#1,413,577
I think they stripped him of his mod permissions would be my guess. You can actually go into a thread and there isn't a bunch of posts missing now. Without being able to control what's in a thread Dave lost the ability to troll and have the control of the responses. He won't come in here using his name and tripcode without being able to delete replies.
Anonymous E joined in and replied with this 5 days ago, 1 hour later, 7 hours after the original post[^][v]#1,413,584
His absence isn't literal, it's lateral. You're never going to understand what's happening if you look at the situation literally. But if you think about it laterally, it's quite obvious.