What I want to know is whether Richard P. Gabriel ever had business success with LISP rather than just academic success. A quick scan of wikipedia doesn't mention any modern businesses.
For quite a few years now, he's been the chairman of OOPSLA (now renamed to SPLASH), which I find quite ironic.
But (if I understand the timeline) by the time he wrote that, the prior business had been dead and buried for 7 or 8 years. Reading between the lines, I think they attached themselves to a platform that looked good (symbolics) at the time, but which failed to capitalise on it's potential. Essentially they were in the accessories aftermarket... and if that market disappears you'll go down with it.