It's not his reasoning, actually. He's just quoting Brown v. Hot, Sexy and Safer Productions, the relevant 1st Circuit precedent (which, btw, is precedent he's required to follow).
For anyone not acquainted with the jr. high school presentation, check this link to the court case. It was even worse than it sounds.
The plaintiffs' complaint alleges the following facts, which we take as true for purposes of this appeal. On April 8, 1992, Mesiti and Silva attended a mandatory, school-wide "assembly" at Chelmsford High School. Both students were fifteen years old at the time. The assembly consisted of a ninety-minute presentation characterized by the defendants as an AIDS awareness program (the "Program"). The Program was staged by defendant Suzi Landolphi ("Landolphi"), contracting through defendant Hot, Sexy, and Safer, Inc., a corporation wholly owned by Landolphi.The parents lost this Massachusetts case, 13 years ago. This judge's ruling is only recognizing the status quo.Plaintiffs allege that Landolphi gave sexually explicit monologues and participated in sexually suggestive skits with several minors chosen from the audience. Specifically, the complaint alleges that Landolphi:
1) told the students that they were going to have a "group sexual experience, with audience participation";
2) used profane, lewd, and lascivious language to describe body parts and excretory functions;
3) advocated and approved oral sex, masturbation, homosexual sexual activity, and condom use during promiscuous premarital sex;
4) simulated masturbation;
5) characterized the loose pants worn by one minor as "erection wear";
6) referred to being in "deep sh--" after anal sex;
7) had a male minor lick an oversized condom with her, after which she had a female minor pull it over the male minor's entire head and blow it up;
8) encouraged a male minor to display his "orgasm face" with her for the camera;
9) informed a male minor that he was not having enough orgasms;
10) closely inspected a minor and told him he had a "nice butt"; and
11) made eighteen references to orgasms, six references to male genitals, and eight references to female genitals.
Plaintiffs maintain that the sexually explicit nature of Landolphi's speech and behavior humiliated and intimidated Mesiti and Silva. Moreover, many students copied Landolphi's routines and generally displayed overtly sexual behavior in the weeks following the Program, allegedly exacerbating the minors' harassment.