So why not baptize the baby? He’s an innocent who has nothing to with the issues raised by the Vicar.
This is because baptism of an infant or child presupposes that the parents will raise him in the Catholic faith. The godparent(s) must be Catholic, too.
Otherwise it's a hollow, or even a hypocritical gesture. Who makes the Baptismal promises on behalf of the child? What do they mean by it--- if not that they are (or are willing to be) "conformed to Christ" in their faith and morals?
In this case, the lesbian couple went, not to the Catholic Church, but to the Church of England, and I'm in no position to say what they mean by their Baptismal promises.