Yes, I think they would "dare" say it. Plenty have before. On the other hand, it's not clear that there is any justification for such claims, at least not in general. Obviously some gay couples can be bad parents, but that's going to be down to other personality traits rather than their sexuality.
A lot of the complaints surrounding this sort of story seem to me to make little sense. "A dangerous social experiment", some people have called it. Why? Why is it any more dangerous to allow gay couples to become parents, having perhaps gone through certain control procedures, than to just let same-sex couples procreate willy-nilly with almost no control whatever for thousands of years? Who knows, perhaps more state involvement in who gets to have children could be a good thing. (I'm not exactly being serious here, but still it surprises me that this is regarded as a social experiment particularly, rather than all the others that go on that are ignored because they fit nicer with people's world views.)
Then there's the other argument that children need both a father figure and mother figure in their lives. There might be rather more justification for this point, but then on the other hand I don't think that it's fair to say that one can't be a father/ mother figure because of what's inside your pants, or not. Fatherhood and motherhood roles are to a large extent defined by how people interact with children, rather than who is doing the interaction, and there is certainly every possibility for two men or two women to provide "both" roles. These things can be very tricky to define exactly, but if motherhood includes spending more time with the children when little, and fatherhood perhaps is the authority figure in the household, then in my childhood I think it's pretty much fair to say that my Dad played the mother figure and my Mum was the father. Make of that what you will.
Again, it comes down to the couple/ single parent in question, and any statements along the lines of "same-sex parents are better/ worse than heterosexual parents" might be statistically true as a whole but totally irrelevant in decided whether or not this couple should be able to have a child.