afaik he was not much of a contributor to the open source arena. He was however one of very few lisp programmers who had a job, programming in lisp. Someone pointed out that he wrote a billing system among other.
Anybody can be paid to write "lisp" for a living, just work closely with small business owners and provide them with "software solutions". I have been a working Lisper since 2001, pretty much since I bought Winston and Horn and started replacing C++ with it, but I digress.