ratzz, from what I read in the past, he OFFERED a refund to anyone who didn't want to wait, and at least some people decided they'd rather wait than get a refund. So no, there is no deadline until someone requests the refund or he says that the project is dead.
And I'm sure Saint didn't offer to send you his book and let you pay at some later time, so that is totally unlike this situation. These people paid with the understanding that it was a pre-order, so it was completely willing on their part.
You don't have to like David's methods, his products, his business, or whatever, but that doesn't mean he's a bad guy. A lot of us (myself included) have gotten good stuff for free or for purchase from him, so at this point he seems to only have positive transactions. Of course, if he has disappeared and won't refund people their pre-order money, that's a different story.