If I create an open source project I can run it however I want.
I do not have to create a board to manage it, there are plenty that have a single developer doing all the work, like VLC, and like Sqlite they may or may not even accept PRs. It doesn't stop it being open source.
If I do create a foundation, I can fill it with whoever I see fit. If there is a board, then generally they have the last say but there are plenty of projects, like Python used to be, where there might be a board but the founder remains the benevolent dictator for life and will stop them doing stupid things that distracts from the core project. Look at Linux, the project is mostly self maintained but Linus will gatekeep anything that doesn't meet his definition of success.
If my rules for my project is that all board members have to be a furry, then that's my right, and maybe the board of furries will vote to overturn that. Or maybe they won't. But you can't tell me how to run my project, this isn't a democracy.