Author of the pr gave stuff for free. He showed no signs of entitlement. But he is not there only one who gave stuff for free. The open source project gave code for free that is 100 times bigger than the pr. Not acknowledging that is a problem.
What we do know, is the maintainer chose to ignore any communication related to this PR, for months, until someone pointed out it was helpful keeping the PR open, as it allowed people to apply it themselves locally. Then, all of a sudden, the PR is closed, and communication finally occurs. Could be coincidence, but that's doubtful considering the time span and specific comment involved.
Which is entirely their prerogative. All they did was build something and give it away for free.
As I said, it's a culture of entitlement that drives people to think that anyone's PR should be looked at is owed.