If homosexuals were required to state on their health insurance forms their sexual preference, do you think they would be able to afford the premiums that actuaries would set for them, given all the health problems that come part and parcel with homosexuality? Of course not.
The broader heterosexual community is subsidizing the gay lifestyle. They can't survive without heterosexuals. Thus, if I'm paying for it, I can regulate it.
Same argument as communists and fascists use.
Paying out way more money for the elderly - perhaps we should make that illegal too?
So rather than attack the problem of socialized costs, you would rather grant power to the government to regulate every behavior that could conceivably impose a cost on another (i.e. everything). And you're a conservative?
Obviously homosexual activity opposes the common good or the common welfare. Well, it used to be obvious, anyway.