While I completely get what Zed is saying about asking permission. I don't think that "porting" a book is lacking class. It may turn out to be a futile effort, but in many ways I saw it as a tribute and maybe learning exercise. It would be a blast to do SICP in Java. For Java programmers the process of writing, and for others reading such a book would be a valuable experience.
I think if Zed would have just said:
"Hi, my book isn't public domain. You can't modify and redist w/o permission. And unfortunately, I don't think Ruby is the type of language you can just drop in as a replacement for Python. You may get the result to work, but it'll be suboptimal for Ruby and may even make my original text look worse as a result.
Ther eare some people working on a clean room version with Ruby. If you're interested, I'd be happy to make an introduction for you. Again, I'll have to ask you to cease using my text for this project, but hopefully you can create a great Ruby book in some other manner." Or something similar, the result would have been a more civil dialog.