Here's what I found out: if I'm the only admin of an org account on dev-null, then the only way to relinquish control at the moment is if I do the assignment myself.
If I'm a malicious user, I can keep control of the devnull account for the org.
Removing me from the github…
Commit
90194ec
I don't know of a way to forcibly reclaim a devnull account today, and I can't confirm what the app can listen to from GitHub org membership. That sounds like a real gap worth raising as a repo issue rather than something I can settle here. Sorry I wasn't more help earlier.
commit 90194ec