What's the Deal?

My little town was host yesterday to a "press conference" held by about a dozen opponents of a bill to legalize same-sex marriage in the state of California. Why this meeting of intolerant bigots, no larger than many a Rotary club breakfast or a senior citizens shopping trip, was deemed worthy of front-page-local-section coverage in my local paper is a question worth pondering.
But even more mystifying is the argument these so-called "Christians" make that same-sex marriage would be harmful to heterosexual marriage. One of the leaders of this band of thugs is quoted as saying that legalizing same-sex marriage would send dangerous "mixed messages" to young people.
For years I have wondered this: Are these people afraid that heterosexuality couldn't hold its own in a free market?