I seem to remember other programming languages (and programs that run code not included with the application) being banned on the app store. Did something change? Or are you compiling down to JavaScript to get around the limits?
However, I don't think they dropped the rule against being able to download code. If this thing lets you load files from the net that are interpreted as Scheme programs, it could be in violation of that rule.
That would be all you need for e.g. Emacs.
Edit: I checked, the rule is a bit unclear but the discussion seemed to be just about downloaded content. Emacs is possible. For a phone, which should be able to handle visa card info etc, I guess this is reasonable.