That sounds like something to score brownie points.
In reality, with their millions, there's nothing stopping them from re-Lisping it.
(Not even time considerations -- when they were in negotiations to be acquired, they didn't do any development for months [1]. If you can get away with spending that much time not developing before you have money, you can get away with doing a rewrite after money is no longer a concern.)
"Incidentally, the last straw, I've been told, was some bug in CMUCL threads that kept making the system crash."
http://groups.google.com/group/comp.lang.lisp/msg/574d19d5e7...