It wasn’t really the man-on-man kiss or the simulated oral sex that marked Adam Lambert’s performance on the American Music Awards on Sunday as shocking. Mostly it was ABC’s reaction. By rescinding Mr. Lambert’s invitation to sing on “Good Morning America,” ABC self-protectively drew a line that networks usually prefer to keep blurred.

Or as Mr. Lambert said Wednesday morning on “The Early Show” on CBS, “There’s a lot of very adult material on the A.M.A.’s this year, and I know I wasn’t the only one.” Mr. Lambert, runner-up on this year’s “American Idol,” was referring to other risqué performances Sunday night, including Lady Gaga smashing whiskey bottles, Janet Jackson grabbing a male dancer’s crotch and Eminem talking about his character Slim Shady’s rap sheet of rape, assault and murder.

There is a lot of very adult material on television all the time, and mostly it flows unchecked and unpunished, except when it comes as a surprise and hits a nerve. Community standards are mutable and vague; lots of people don’t know obscenity until someone else sees it. Ms. Jackson transgressed during the 2004 Super Bowl halftime show because she exposed a nipple, which is one thing that network television normally doesn’t show. Mr. Lambert, who just released his first album, startled viewers because he did things akin to what outré rappers and female pop stars have performed onstage to get attention, only he did it as a gay man.

CBS, which eagerly invited Mr. Lambert to its morning show after ABC canceled, savored its rival’s discomfort. CBS is still fighting a $550,000 Federal Communications Commission fine in the Jackson “wardrobe malfunction,” but at the time it wasn’t any braver than ABC about defending a suddenly controversial star. After the incident CBS disinvited Ms. Jackson from the Grammy Awards that followed, even though it allowed her Super Bowl bodice ripper, Justin Timberlake, to attend.

The Jackson case showed that indecency lies in the context. People complained that children were watching during the Super Bowl halftime show; viewers normally don’t expect to see soft-core pornography until the commercials.

Mr. Lambert’s context was different, mostly because he is gay and his song “For Your Entertainment” is graphically sexual, with intimations of sadomasochism and oral sex. Straight sadomasochism is suggested all the time in music videos, and early this season Courteney Cox’s character on the ABC sitcom “Cougar Town” was coyly depicted performing oral sex on a younger man.

Television has embraced openly gay male entertainers like Neil Patrick Harris, and gay characters are on soap operas, sitcoms and dramas, notably two men who’ve adopted a baby on ABC’s new hit “Modern Family.” But while gay sexuality is discussed and joked about plenty, rarely are the gay characters shown having sex or kissing passionately. The joke in “Modern Family” is that the gay couple’s relationship is as bourgeois and unlibidinous as that of any long-married suburban couple. (“Oz,” a stark and explicit drama about men in prison, was shown on HBO, a pay cable network.) Women kissing women is far more common, probably because it doesn’t offend: for many viewers, two women romping together in bed registers less as lesbianism than as an extracurricular turn-on for men. Girl-on-girl action is a standing salacious joke on prime-time sitcoms like CBS’s “Two and a Half Men.” And respectful depictions of lesbian love are on shows like ABC’s “Grey’s Anatomy.”

Madonna’s infamous smooch with Britney Spears at the 2003 Video Music Awards was a hot topic, so to speak, but no network blackballed them as a result. Mr. Lambert had a point when he complained on “The Early Show” about a double standard.

“Good Morning America” justified its censure of Mr. Lambert by stating that his performance on Sunday went beyond anything he did in rehearsal (true), and ABC didn’t want to risk exposing its viewers to a spectacle of similar debauchery first thing in the morning (not very likely). Instead “Good Morning America” hosts lavished attention on squeaky clean Donny Osmond, the winner of “Dancing With the Stars.” Mr. Lambert acknowledged that he got carried away in the live performance but said that if he could do it over, he would do only one thing differently. “I would sing it a little bit better.”

It wasn’t the best musical performance by any means, but it wasn’t the worst display of sexual debauchery either. Mostly it was a reminder of television’s policy regarding gay men: Do tell, just don’t show.