My reading of the above is that Stallman is exerting hegemonic control, thus being the (or possibly one of) the controllers of the hegemony. I agree with the original poster that this assertion is laughable at best.
But since the free software model was so successful, many people worked hard to remove its political associations, creating the open source movement. I think the real hegemony is the collection of existing power structures, which will always work to assimilate successful models.
It's important to think about who benefits in social interactions, but a useful analysis requires understanding particular historical details like the animosity between idealists and pragmatists in the FLOSS community. It might have been more useful to state that despite its idealiatic origins and the continued participation of people who want to address social problems with software, old structures of privilege continue to determine who benefits from social interactions. Anyone who disagrees with these privileges must take care to decide how best to work against them, because the default benefit is always to those who have inherited privileges.
Wikipedia is pretty okay too: http://en.wikipedia.org/wiki/Commodity_fetishism
Basically, commodity fetishism is the notion that economics is about relationships between commodities, not about relationships between people. It's called 'fetishism' as an allusion to religions in which dolls come to life. Marx asserts that economics is about relationships between people, but since we focus so much on things, the things come to life, like a fetish, and become just as much a part of our notions of economics as people are.
It relates to OSS because of 'the fetishizing of the F/OSS community itself': the dozens of articles about how OSS is the best way to make software, the only good way to make software, that those who do OSS are better than those who don't. We animate this social relation and put it on the same footing as actual people. They're expressed through objects.
Does that start to make some sense?
Stallman is an example in the article, not the controller of the hegemony. The hegemony is of the fetish of Open Source. Stallman is just one person (I am very much another) who stands to benefit from the hegemony.
I understood 'bug, not a feature' in a different way than you. What I got out of it was that it's a structural, not accidental aspect of the system. She was attempting to bridge the culture gap by referencing hacker pop culture. This kind of commentary is very common in Marxism.
I'm going to go eat lunch now, I'll check back in on this discussion later. Thanks!