Yes, the average man is bigger and stronger than the average woman. Generally under the conditions you've described this is the case - but the wider case being made here, albeit quite gently is that the Powerlifting world isn't mitigating against outliers. Rae-Ann Miller is stronger than both Anne Andres and Avi Silverberg - and she is a cis-woman. Given that both Silverberg and Andres are not as strong as the strongest cis-woman, is the distinction enforced in most women vs trans-women arguments at all meaningful?

In short, if we're happy to accept that the strongest woman is Rae-Ann Miller and she is a cis-woman, why would we not accept the validity of lifts by trans-women who aren't as strong? They may be stronger than average, but by definition they still fall within the range of women's strength.