That's a completely invalid reason/excuse, unless you also agree with the statement that "because some conservative Christians are anti-gay, and harass gay persons, all conservative Christians should be ridiculed and labeled with the term homophobe, or similar".
First, you assume that a parent being gay would tear said family apart – dismissing any other possibility.
Second, there is no logical connection between some random lesbian couple and someone’s gay parent – unless one of the lesbian couple’s halves was one of his parents, in which case that would probably have been mentioned in the story…
First, you assume that anyone needs to legitimize something that was never de-legitimized in the first place.
Second, you assume that the activities you’ve previously mentioned are immoral
Third, you assume that the activities you’ve previously mentioned are “perversions” and thus need to be accepted.
Fourth, you assume that society is a static thing, which needs to be unchanging for it to survive – also highlighted in your “destroys the fabric of civilization” phrase.
The insidious aspect of these assumptions is that all those statements are possibly true, but are at the same time completely baseless – or rather, based on (I suspect) beliefs which are in turn baseless and unproven.
As such, you are completely entitled to hold said beliefs – as it’s not up to the government (or it shouldn’t be) to dictate what people should and should not think.
However, it’s also highly ironic for you to be advocating that gay persons keep their personal morality to themselves while at the same time shoving your own morality into the limelight and demanding that it be accepted as the standard.