However, I have some criticism over the way it's been handled, and I'd like to point out before saying it that it's not a personal attack, just some observations. I don't use Cap but I do use net/ssh and I'm very grateful for Buck's contributions. However ...
It's his right to walk away, and as he points out, he owes the community nothing. But it's still a bit weird and passive-aggresive, the way he's done it. Healthy human interaction in a situation like this would be polite but insistent assertiveness; defining your limits and consistently sticking to them, not holding it in, getting silently angrier and more pissed off, then quitting in a blaze of defensiveness.
There are techniques for dealing with users/contributors, distributing the load so no one person is overwhelmed. Capistrano's documentation, for example, was/is awful. The website has almost nothing useful. The way to learn how to use it is to perform any number of searches for people talking about how they did it on their blogs, and then doing it yourself by trial and error. Or the entitled newbie way, which is to pile on the mailing list, where their questions were foolishly answered, attracting ever more entitled newbies looking to have their problems solved for them, causing stress. Decent documentation would have solved a lot of that.
And overloaded with feature requests/patches? There are websites for handling feature requests, and the developer should have insisted on nothing but properly tested patches fixing a known bug. Wouldn't that have gotten the situation more under control? Or hell, why not roll cap into Rails proper and spread the load that way?
It's all just a bit suboptimal, is all. Oh well. Good luck to the dev. Hopefully other projects can also learn from the experience.