As such, it's up to him to try and prove his statement. In no way he can do that. So why does he make it an unquestionable truth?
Conjecture will lead nowhere because obviously he already established his bias in a very clear way. Meanwhile, to reduce this argument to well known established Open Source software is really missing the point that the Open Source movement is much larger than these projects. And like with closed source software, there are the good, the bad and the outright ugly.