Comment by ShamblingMound

It certainly is considered harm. Ethical research with human subjects makes every effort to do no harm.

Taking someone's time without compensating them can be harmful. That's why researchers often give gift cards or small amounts of money for filling out surveys.

It's not always as straightforward as paying participants, but compensating participants for their time should be a consideration in ethical research with human subjects.

I don't know how much time the kernel maintainers spent on these patches or what their time is worth, but I'm certain that the time they spent on this is worth way more than the nothing they got in return.

The uncompensated time that maintainers spent on this is harm. And that anger that you imagine you would feel is harm. Ethical research with human subjects tries to avoid causing this kind of harm, and there seems to have been no such effort in this research design. This was not ethical research.