I don't agree that if they can't lead the program, that means they are being prevented from having a meaningful opinion about it. That's all they're talking about, right? Who leads the program?

Yes, presumably the leaders are to issue orders and everyone else is to follow them. That is not the kind of participation that allows opinions.

You may be saying that the non-white leadership is the kind of leadership that allows collaboration and influence from followers, which is what I would do, but the evidence in the Github case is to the contrary.

Considering that they are moving to a more enterprise-y management style where there are lots of middle managers, I would imagine that that is a very real possibility.