Specific meaning of term "nail-biters" in context of mid-1970s America

The phrase in question revolves around a rather odious quote, so I beseech all reading to please suppress your political leanings and focus instead on the meanings of the phrases employed.

In around 1977, Anita Bryant, singer and vocal celebrity advocate of the "Save our Children" campaign aimed at curtailing the freedoms of American LGBT citizens, stated:

"If gays are granted rights, next we'll have to give rights to prostitutes and to people who sleep with St. Bernards and to nail biters."

My fascination focuses on the last part of her sentence - what on earth constitutes a "nail-biter"? Surely Anita Bryant didn't hate onychophagists quite that much?

She may have been conflating the usual "slippery slope" argument that legitimizing homosexual behavior would lead to legitimized bestiality and incest with the argument that homosexuals should not be a 'protected group'.

I submit this excerpt from "The Gay Revolution: The Story of the Struggle".

The quote is contemporary with that of Bryant's, and she was a Miami resident at the time.