It was allowed to force push to the main branch. Not "made" by GitHub seems to be quite uncharitable nitpicking, when the bot has been blessed by GitHub and implicitly its actions endorsed.
In the spirit of your comment: Gas lighting is a classic pastime.
It force-pushed to a branch of its own fork, then closed its own pull request without merging it – both things any account can do. No GitHub blessing was ever involved.
And so we move from uninformed speculation to uninformed misinterpretation.