Oh but it is. Completely irrelevant. The disagreement did not prevent the creation of this derivative work, so then it is not going to prevent the use of this derivative work. The attempt to do so is hypocritical.
As I said, it feels needlessly tacked on, pointlessly divisive and unnecessarily hostile. It is against diversity of opinions, against equity and inclusion of people holding differing opinions. And as someone who also thinks JKR is a hypocrite, this just reads like a spoilt toddler throwing a tantrum - it reflects badly on all of us and is frankly quite embarrassing.
And all for what? What possible purpose does it serve? Those who agree don't need to hear it; those who disagree don't want to hear it; and nobody else cares beyond finding it pathetic and in bad taste. It's so mindlessly self-destructive.