>>194
Read time - building objects from s-expressions (program text as character stream), interns all the symbols, etc.
Evaluation time - operates on objects in memory, this is where the actual magic happens
Now, I have no idea how Clojure works, and don't really feel like reading much about it, but it seems that you use a standard macro to create a namespace. Macros expand into actual Lisp code to execute, and the execution should happen on a level above Read; Eval. I'd hazard a guess that he doesn't like that this work is done at Eval step, since generally you want to do this at Read step, when symbols are interned. The way they seem to want to do it in Emacs looks similar in spirit to reader macros, so they do work at read time.
You have to keep in mind that Stallman is an old school Lisp hacker, and has VERY strong opinions on it. If I remember correctly, he hates lexical variables (and dislikes Lisps that use them), doesn't take too kindly to Common Lisp in general, and so on. This, combined with the fact that Emacs Lisp had to start small due to resource constraints, is the reason why it's sometimes difficult to work with, and why libraries like cl-lib and friends have been developed.