Its the only choice they have to sound "conservative" in this debate. They have to change the entire debate from private acts to public indecency. The funny thing is, given that gays are such a small percentage of the population, public sex among heterosexuals is way more widespread.
There are swingers clubs but many more bath houses. There is no cruising in the city parks for heterosexuals seeking anonymous sex in the bathrooms.
Some nightclubs may have members of the opposite sex having sex in bathrooms but you'd likely find more members of the sex sex having sex there (less obvious when walking in and out of the bathroom).
Where are the heterosexuals having their public sexual encounters? Are there glory holes in the wall for heterosexuals?
Women seem a bit more reserved than that. Outside of prostitution, I don't know that many women would consent to "here on the spot" sex acts.