I am dubious of your intermediate and final claims. For something to be necessary, it means that one cannot go without it. Is procreation a biological imperative, with strong positive reinforcement from the individual’s biological feedbacks? Sure. But is it necessary? Strictly, no.

I don’t think you can make the claim that someone saying it is not necessary is inherently biased. To claim that procreation is not strictly necessary is a neutral, objectively true position. The bias in the perspective of “child-free” is the implied framing of the lack of procreation as a personal or moral good. Procreation is, again, unnecessary, and is (in many ways literally) a burden. Whether one frames that unnecessary burden as positive or negative is at issue here.

I don’t appreciate the claim that people must be biased in order to observe simple facts, denuded of emotion.