I think it would be interesting to point out a somehow similar exchange between Richard Stallman and Bruno Haible, the original author of CLISP[1]. Bruno wanted to integrate GNU Readline into the then-proprietary CLISP, but RMS informed him that doing so would be a violation of GPL. After a minor flamewar-of-a-kind, Bruno concurred, because he wanted very much to use Readline, and today the world is richer for another free software Common Lisp implementation. I think it very clearly illustrates how often people don't understand the implications of free software licenses, an issue that, even now when there are loads of FAQs and websites dedicated to just that, remains present.

[1]: http://clisp.cvs.sourceforge.net/viewvc/clisp/clisp/doc/Why-...