To me that means she wants him to be an influence on her child, his grandchild.
Naturally she is not going to be homophobic but she IS a right-winger and will probably raise her kid as a right-winger. Just because someone is part of a marginalized group does not mean they will not support the powerful against the weak. Do some reading about the Court Jews of the Middle Ages. From what I know of Mary Cheney she has never sided with the weak against the powerful.
http://bbsnews.net/index.php?topic=gaymarriagesnip
In Virginia, where more people voted for the marriage discrimination amendment then for either Senate candidate, there is no warranty for Mary and Heather that some state entity might not swoop in and take their child from them because they are unfit because some bigoted Christianists push the issue. Mary Cheney has been a part of the GOP attack machine because she has helped mightily those that want to discriminate against her growing family: Heather and now their new baby. That is unfortunate.
She would be better off to move from Virginia to Massachusetts. They could get married as residents and then bring up their child in a state that is leading the rest in equal rights for gays. And it would be nice if she stood up to her father and the party of discrimination that he belongs to. And she should admit to herself and the public that she helped to marginalize along with him a huge American constituency that includes -- herself.