Sooner or later, at least the premise of your suggestion is bound to occur, if it hasn't already, in venues that decree benefits to "same sex partners."
If you are a single straight person, with a friend or relative of the same gender, who is in dire need of medical treatment, but cannot afford it, and, you work for an employer who offers free group insurance benefits to "same sex partners", it would make perfect sense to sign that person up as your "partner" in order to save his or her life.
As legal, social, commercial, etc. benefits to homosexuals increase, it will be increasingly tempting to foist oneself off as "gay", simply to avoid massive reverse discrimination.
Some years back, I began work on a piece of "fiction" (it's so difficult to stay ahead of the reality curve), in which the government, in order to prevent "abuses" of this "right", required homosexuals to submit proofs of their... "orientation". I leave the gory details to the reader's imagination.
We are headed down a path from which there is no return. Society is embracing a disease which has no cure, no remedy, no treatment, other than allowing it to run its course.
The name of this disease is not "homosexualty". The name of this disease is "madness."