I think the market forces argument is overstated with languages like Lisp, Haskell and ML that have very devoted users. I believe, but cannot prove that hiring for a Lisp job in an area with a large programmer population would be at least as easy as hiring for a Java job. The mere fact of being a Lisp job would tend to attract the Lispers; there would be applicants. Certainly, they would be fewer than for a Java job, but that's not a bad thing; the hiring process often involves spending a massive amount of time weeding out people who are too inept to even consider. There are very few Lispers who are too inept to consider for most Lisp programming jobs.
Postscript: Many of the multi-language integration headaches were caused by the interprocess communication system that allowed Lisp and C to communicate. The IPC relied on a central server (written in C) which crashed regularly. Getting rid of Lisp did in fact alleviate those problems (because the unreliable IPC was no longer necessary). It is nonetheless supremely ironic that the demise of Lisp at JPL was ultimately due in no small measure to the unreliability of a C program. """
For example,
"Someone (I don't know who) interrupted him [the software integration engineer] and asked if he could change only one thing to make things better what would it be. His answer was: get rid of Lisp. That one event was pretty much the end of Lisp at JPL."
Why did the integration engineer say that? This should be the cornerstone of the article. Same thing goes for the Google discussion he quotes.
Also, the author doesn't seem to take market forces into effect, eg. given that C++/Java became the dominant languages, I'm almost certain there were (are) not enough Lisp programmers on the market for Lisp to be a feasible technology at a large organization.