I already know both languages — in fact, I've known Objective-C for 10 years and Ruby for only six — and I still see some reasons why this is interesting.
Anecdote: When ARC was first released, I decided to turn it on for a small project. The very first method I wrote blew up with a memory error. The reason? I used the NSFontMatrixAttribute of NSFontDescriptor. For some reason, ARC doesn't handle it correctly. I've never had such a thing happen in Ruby.
There is still a long way to go from where Objective-C is. It's moving in the right direction, but there's still a long road ahead of it. Ruby is closer to being there, though the lack of tool support (particularly autocomplete) makes it a much less compelling proposition than it would otherwise be.
Also, Ruby can be considerably easier than Objective-C to read because there is a lot less line noise. Objective-C's method names read very smoothly out loud, but they can also be visually overwhelming at times and make code sort of melt together into a wall of text. It's maybe a little bit easier to read Objective-C quickly when you're being very deliberate about it, but it's much easier to skim Ruby in my experience.
I probably won't be using this, and I think your criticism of Rubyists is kind of valid, but I think — for this particular project — you're dismissing it too readily.