I don't agree that serial killers are disproportionately hetrosexual as indicated here. Dean Corril, John Wayne Gacy, Larry Eyler, Randy Kraft, Wayne Williams, Robert Burdella and Jeffery Dahmer were all notorious homosexual serial killers. In fact I would bet the homosexuals constitute a greater percentage of serial killers then their percentage of the population at large.
Having been personally involved with investigations in two of the examples you named, I'd say based on that and other experience that you're probably right, up to a point. But too, the habits and inclinations of homosexuals for engaging in impulsive risk behaviour and a mindset that ignores social attitudes as to norms and aberrance constitutes a handicap for their chances of long-term success. I'd bet that a larger proportion of homosexuals are both undeterred by legalities or moral strictures against killing, but they're probably caught in larger numbers as well.
The quiet guy who kills those unknown to him and usually in a location where he's transient or unknown has all the chances in his favour for continued success, whatever his sexual inclination may be. And the women who engage in such activities almost always manage to slip between the cracks of investigations, so long as they keep their mouths shut.
You left out Herb Baumeister, among at least a dozen other murderous notables. And many of those who prey on females- Tom Schiro and Bill Benefiel come to mind- are homesexuals whose prediliction for female victims is seated either in contempt or hatred, jealousy of real females, or simply because their potential victims are less of a physical threat.
And then, of course, there's Aileen Wuornos. I don't know exactly how you'd characterise her preferences, but a study of the blood trail suggests that it was not pretty.
In the smallish southern Indiana town where I plyed the trade of newspaperman from 1988 to 2001, we had no fewer than twelve serial killers whose paths crossed here, some related, some not- and probably more.