I think it just means that Gabe decided to dad-up and finally get rid of some folks who were hanging around not contributing much. My guess is that with their management structure it makes it awkward to get rid of people so that list was just filling up.
Steam sales -> we have greenlight and want a self-publishing API Hardware -> we picked up too many of you guys and it turns out we're probably not going to be making hardware Everyone else -> culture clashes / not contributing
And like I said earlier I doubt these people were let go without some significant help. I'd bet they even knew ahead of time.