It is a multi-faceted issue. Both the customer and the company are victims of Amazon.
It’s not the company’s fault that the diaper was re-sold, so they don’t deserve to have that negative review. It’s true that the review was against Amazon’s policy. Whatever you make of that policy, Amazon should have removed the review when asked.
Meanwhile, it’s not the customer’s fault and you can’t blame them for making such a review.
Ultimately it’s Amazon’s fault for re-selling the diaper and for not removing the review when asked. Both are bad decisions Amazon made. The customer is a victim of one decision, and the company is a victim of the other.
This is a fair criticism.
From my read, other details mentioned that the reviewer realized and mentioned that they suspected the item was returned and not inspected before being re-sold. This makes the review about the return process, not about the item itself.