You obviously know more about this situation than I do, so I'm not going to be able to win any rational argument unless you choose to disclose more details.
I get your suggestion of hubris here, but again, I'm speaking from experience. I've done the solo technical founder thing, and that came with a whole host of problems that seemed unsolvable and which I didn't have anyone to appeal to for answers. Those are the problems that taught me most of what I know - most importantly that when you run into something that you don't understand, it's an opportunity to learn about it and solve it, rather than to just give up. In the Rails world, where the entire software stack is open-source down to the kernel it runs on, there is literally nothing to get in the way of understanding what's happening at any point of the application's execution.
I'll reiterate that if you want to do a writeup on why your circumstances were unique, and the problems you faced which were so crippling that they forced a rewrite, I'd love to read it. The suggestion that Rails 3 has landmines so critical in it that it necessitated a full product rewrite in Rails 2 is exceptionally weighty and should not be asserted without a very specific cataloging of what those problems are. That particular assertion - "Rails 3 has problems that cost us $XX,XXX and the Rails Core team doesn't have a clue what they are" - is a big one.