I agree, but no need to guess, Its not uncommon to do things without financial motivation:

Bureau of Labour Statistics
http://www.bls.gov/news.release/volun.nr0.htm
"Among employed persons, 28.9 percent volunteered during the year ending in September 2008."

In my mind the anxiety about commercial interests in open source, and as by product the paying of developers, is not misplaced. Plenty of good things have been turned to shit once business was introduced. Anyone with half a brain can observed that the idea of capitalist competition spurring development is more the exception than the rule. Companies soon catch on that its easier to FUD, lie, distort, lock-in, lock-out, patent harass, sue etc etc than actually compete by developing better products in the spirit of capitalist competition theory. The more dominated by devious profit-is-king sell-your-mother-for-a-percentage minded capitalist stakeholders in the open source eco-system the more risk to open source from its toxic ideology ie Tivoisation, trusted computing, DRM, software patent.

Anxiety can be a good motivator but paranoia leads to disaster. It is observably true that, while not there at the start, capitalist institutions have pushed forward the quality and quantity of open source by pouring in the massive resources they have. However so far no death blow perversion to open source has been struck. So we must ask what would be the death blow? Specifically who knows but generally anything that effectively denies open source freedom! Its all about freedom, freedom, freedom! Capitalist agendas can and should be allowed to embrace open source but never at the risk of the core freedom loving ideas that birthed the movement. If one doesn't understand those fundamental freedoms that created the open source movement then of course one could easily play a part in killing the golden goose. The only thing that the open source 'community' needs to survive is a freedom loving pulse and, I'm sorry to say, capitalism isn't historically known for this and wage enslaved employees aren't, by definition, in a position to dictate policy.