Stallman is the enemy of your Lisp!

http://www.gnu.org/prep/standards/html_node/Source-Language.html#Source-Language
>in general it is much better to use C, rather than the comparable alternatives.
>C has one advantage over other compiled languages: more people know C
>the best language to use is C. Using another language is like using a non-standard feature: it will cause trouble for users.

>>1
Stallman actually prefers hacking in Lisp, he envisioned GNU to be written in C and extended in Lisp. This advice is just a matter of practicality: more people know C than other compiled languages.

>>2
The GNU weenies adhere to the standards when it makes sense and they are also not afraid of extending features when they see fit.