You truly aren't understanding why your position is nonsensical, and that's hilarious to me.

In my example, if you were to disagree with the claim that bears aren't living on the moon, then the only way to prove one way or the other is to show evidence that bears do live on the moon. That's not my claim, so I'm not charged with finding evidence that bears live on the moon. If you want my proof that they don't, my proof is that there is no evidence that bears do live on the moon. There's no reason to believe that they do. That's as far as a null can be proven. Just look at all the following evidence I've found in all my long searching for evidence of bears living on the moon:

...

Convinced?

For the actual argument here, the claim is that nobody criticize male politicians for not having children. You said prove that nobody has done that. Well, there's no reporting of that criticism, so what, you want a link that goes to 404: page not found? To discredit that claim, you need to prove the negative; find a criticism of a male politician for not having children. If you can't find it, then you haven't refuted the claim.