And assuming bad intentions is a good way to live a miserable unhappy life.
Perhaps because nobody has asked her to do so. Despite the contribution process not being followed, the results are seemingly desirable; and so nobody seems to want to worsen the codebase by reverting the change, even temporarily.
Process is great when it improves quality, but process followed just to follow process—when it won't result in a change in quality—is just pageantry. Engineers are generally too practical (and impatient!) to participate in pageantry, even as an act of public humiliation for someone they're annoyed with.
The repo has other maintainers; any of them could have reverted the merge and demanded the PR process be followed, if they thought it was a good idea to do that. What intent do you derive from their inaction?
The PR is here, it was explicitly rejected (with two comments) and closed before she merged it
It looks like the actual maintainer reverted it?
Since I can't read people's mind, a good trick that I learned is to derive intent from actions. Removing a merged PR is easy, especially when you can force merge one in the first place. Yet she didn't do it, but wrote a lot of text that is apparently an apology. If it's an apology, why is there no show of regret by retracting her PR? Maybe because it's not actually an apology.
Edit: the PR was removed by the current maintainer.