I sort of get what you're trying to do here - an exercise in empathy - but the flip side of this is that he has been made enormously wealthy off the back of thousands and thousands of unpaid volunteer hours on an open source project. It's not only "others" who are getting the financial gains.
Good point and agreed. Do you think for him it is more an issue about how much money WP Engine is making compared to him or the relative influence they have?
I'm not really sure to be honest! He could well be thinking exactly what you said, I was just pointing out the flip side of that argument if that is what he believes, because it would be doing a real disservice to the open source community around WordPress without which he would be nothing.