In answer to your last sentence - not at all.
I expect a gay couple (male or female) to consider the needs of the child rather than their own desires. How they get a baby is irrelevant to me, it's the age that I have a problem with.
Consigning a child to never have the chance of a grandparent or for that child to not have grandparents for their children is cruel in my opinion
To quote my mum and her mum before her, 'Tomorrow isn't promised to any of us'.