GitHub GPG and Keybase PGP

I don't understand what "unverified" means, then. If you can just edit an unverified key into including the right email address, what's unverified about it?

Are they trying to say that the @keybase.io email address has not passed email verification as associated with the account? What's the point of that?

If I compromise someone's git repo (e.g., I trick them into pushing commits they shouldn't have pushed), I shouldn't be able to cause my own key to show up as "verified" as the victim's email address. If the victim needs to approve that key in GitHub's web UI, then what additional benefit does "verified" bring?