"I think it's ... dangerous ..   for a small company."<p>of non compiler/language processing experts.<p>If you've built compilers before and know what you are doing (I have no idea if these guys are such experts or not) , it may be a reasoned decision taken after weighing benefits and costs.<p>Leon Bottou and Yann LeCun seems to have built the Lush dialect of lisp to build commercial systems. (<a href="http://lush.sourceforge.net/credits.html" rel="nofollow">http://lush.sourceforge.net/credits.html</a>)<p>For example, I can easily imagine PG building a variant of lisp and building a product/company around that .
Of course if you only have a vague idea of how to build a  compiler/interpreter/whatever, then building a  company around your first such project may be  ... interesting.