We actually went through tons of different programming paradigms that scheme and lisp probably weren't really designed for, like OO (closures upon closures, all the way down). Throughout the class harvey and the TA's emphasized that everything we were learning could be done in any language, and didn't actually require scheme or lisp (yes, we never got to macros).
I can understand why you it might seem strange to port SICP over to scheme if you read SICP with the intention of learning lisp, but at berkeley the point of using SICP was to iterate through many different programming paradigms and cover basic computer science. unless they've found a better manual for this, it makes a lot of sense to just translate SICP instead of starting from scratch.