Medicine: no biological basis for bisexuality?

To cap off this three part series of controversial research in the news, a study out of Northwestern suggests that bisexual men demonstrate arousal patterns generally consistent with that of homosexual men:

The study, by a team of psychologists in Chicago and Toronto, lends support to those who have long been skeptical that bisexuality is a distinct and stable sexual orientation.

People who claim bisexuality, according to these critics, are usually homosexual, but are ambivalent about their homosexuality or simply closeted. "You're either gay, straight or lying," as some gay men have put it.

In the new study, a team of psychologists directly measured genital arousal patterns in response to images of men and women. The psychologists found that men who identified themselves as bisexual were in fact exclusively aroused by either one sex or the other, usually by other men.

I see a rather large non-sequitur between saying that bisexual men generally demonstrate arousal patterns consistent with homosexual men and saying that bisexuality is not a distinct, stable sexual orientation. Especially given the methodology of simply presenting erotic pictures of males or females, and equating that with the raw force necessary for a person to engage in a sexual encounter or a stable sexual relationship with a member of the same or opposite sex.

The article implies strongly that the etiology of bisexuality in me involves homosexual men who simply can't deal with the idea of being gay, and thus continue having sex with women depsite arousal states consistent with those who exhibit more typical homosexual behavior.

And all that seems like total bullshit to me, since I don't understand why arousal pattern necessitates one's sexual behavior. In the traditional debate, social liberals employ the biological basis of homosexuality, supported by fairly rigorous science as a major trump card against social conservatives who argue without rigorous scientific approach that homosexuality is somehow unnatural, and thus immoral, and thus, sequitur, unGodly. Liberals of all sorts lose arguments against conservatives because we attempt to use the language of conservative logic in our arguments. The biological basis of homosexuality, while seemingly indisputable to the objective mind, really has little to do in the absolute with whether homosexuality is moral, stable, or exists.

As Mr. Kinsey's reports demonstrates clearly, bisexuality exists. There are bisexual males, and bisexual females. There are people who tend to one side or the other, with only occasional deviations, and there are those who are fully equal opportunity employers.

This data does not justify an unnecessary jump to the assertion that bisexuality is neither stable nor a real sexual orientation. Granted, it might be very useful in proposing models of cognition employed by some bisexual individuals, and it might even be relevant for addressing some aspect of the various manifestations of mental illness that occur more often in LGBT individuals.

But straight, gay, or lying? That's a useless paradigm illogically derived from an otherwise imporotant study.