There is obvious a communication issue from the .net foundation but also from the maintainers themselves.
If they ask you for X permission, you cant just say no, sorry but you are part of an organization and it doesnt work that way, one way or another regardless of what was told to you X years ago, things might change and you will need to take an active stance to it.
Horrible move from the foundation to ABUSE their admin rights and move the repo to GitHub Enterprise, but posting a tweet about your emotions and then trying to find a way to move the repo without reaching out to someone is not the way to go.
Most likely even if the person did reach out to someone, the reply would be dry and late, but this is something that has been cultivated by the maintainers as well. As the article mentions "the communication was shit but it was fine as long as it didnt affect me" - not direct quote.
I think both sides need to reconsider their communication channels and behaviors. They both need to understand that one way or another they have an obligation to each other.
I hope communication and transparency will help to not have similar issues in the future.