Well, MacRuby is a language on top of Objective-C. You can use Cocoa with it, but you should be able to use the Chameleon framework too, assuming it is GC-friendly (otherwise, adding GC support shouldn't be hard). His points don't make much sense to me.
MacRuby was version 0.1 about 3 years ago. A lot happened since, and we expect the next release to be our 1.0 RC. For Cocoa development, it's very stable, we haven't received any critical bug report since at least 3 releases.
Hmm, is that really a problem? https://github.com/macruby/macruby is working as expected. I assume you would just type the camel case name once, when cloning the repository.
The default deployment settings will indeed generate a pretty big application, but it is possible to trim out unnecessary stuff (such as the standard library or extensions). Also, we are hopefully dropping i386 support in 0.10, therefore the MacRuby binaries will be 2 times smaller.