This “surrogate” mother stuff is unnatural, so I have no sympathy for people who do it and want everyone to think they are normal.
It's abusive to the child especially because it intentionally destroys the mother-child bond which is so essential to normal childhood development. It is also abusive to the child because it is a reiteration of slavery: turning the child from a person into a commodity exchanged for money in a business deal.
This would be true even if the baby-buyers were a man and a woman.
And the fact that this is two men using "marriage" as a platform for ongoing sexual perversion, is just the crowning indignity.