For me, taking the libertarian stance, gay or not gay, whatever, irrelevant.
American = right to bear arms.
If that individual decides to commit suicide, that is their own choice.
If that individual decides to go on a gun rampage, he or she should be shot by nearby armed Americans and/or police.
Prejudice = pre judging someone based on something they have not yet done or even might ever do. It is unAmerican to presume a person guilty simply by association (perceived association in many cases; for example nobody chooses to be born with a certain skin color, or even perhaps sexual orientation -- I say perhaps because in some cases it seems it is a choice and in other cases not a choice, and either way I think we need to remember all these are individual people and, specifically, American people).
In a nutshell, are they Americans? If so, then add them to the general pool of people with American rights. (That other people freely waive their own rights of arms is their own choice, so long as it does not infringe upon the rights of other Americans to bear arms -- that is the principle of course)