Given the large majority of commits to the Linux kernel are done by people employed by companies to work on it, your starting premise couldn't be further from the truth, let alone the conclusions you draw from it.
Given that they said most open source contributors I think they are right. Most contributors are not contributing to the Linux kernel. Most are contributing to (https://githut.info/) JavaScript packages
I think that's being somewhat generous of an interpretation given the thread of the conversation, which is specifically about drivers. For it to be talking about Open Source developers in general would be a serious pivot.