By now, you surely know of the brouhaha. On Saturday, former British Vogue editor in chief Alexandra Shulman posted a bizarre piece on the Daily Mail taking Helena Christensen to task for the look she wore to Gigi Hadid’s birthday party. By Monday, it had erupted into a social media maelstrom. Playing into the denim theme for the fete at L’Avenue at Saks Fifth Avenue, Christensen paired high-rise, loose-legged jeans with flat sandals and a black lace bustier. Shulman did not approve. The look unleashed her harshest inner school marm and a reactionary talking-to to Christensen and along with her, to all of us women in the 50-plus category about just where we stand in the sensuality stakes. Her take isn’t pretty.

How Christensen looked in her bustier is almost beside the point of Shulman’s tirade. That said, from my vantage point — and social media suggests that legions of people agree — she looked fabulous. And not “fabulous for 50,” but just plain fabulous.

Still, often a good look is in the eye of the beholder, and Shulman has the right to disagree. But would that she had called Christensen to task merely for donning innerwear as outerwear. Instead, Shulman used the outfit as a way into an outrageous affirmation of an old, hideous societal perception that many of us thought was changing.

You think you can be sexy after 50? You think there’s more to sensuality than the ability to bear children? OK, so you can’t do an onstage squat in stilettos like J. Lo, but you like to think that she onstage stiletto-squats for us all? Shulman wants to set you straight — and she goes much further than addressing the question that many women have likely asked themselves at one time or another while looking in the mirror (I surely have): Am I too old for this? Her message couldn’t be worse: Ladies, grab the knitting needles and head for the rocker. There’s not much else for you. (Can’t knit? You’re really screwed.)

“While men can receive sex symbol status until they are in their box, for women it’s more complicated. As a society, we are frightened of sexuality that doesn’t come accompanied by fertility…” Shulman wrote.

“When women’s bodies no longer serve any child-bearing purpose, we find flaunting them disturbing and slightly tragic. I don’t claim that this is fair. But it’s true.”

It’s true as long as people perpetuate the belief that it’s true. And women, particularly women like Shulman, women with a world view and more importantly, a voice in the culture, should be at the forefront of shattering the stereotype, not playing into it.

Not surprisingly, legions of women and men came to Christensen’s defense on social media. “You are BEAUTIFUL inside and out,” wrote current British Vogue editor Edward Enninful. “She should be ashamed of herself. You are a goddess,” offered Linda Evangelista.  And from Julianne Moore, “U always do, my beautiful friend.”

Christensen’s high-road take on the situation was: “Let’s continue to elevate and support each other, all you beautiful, smart, fun, sexy, hard working, talented, nurturing women out there.”

Big picture, Shulman’s assault on women who are no longer 30 — and it reads like an assault — shocks. Small picture, she did something else you shouldn’t do –– project a motive onto Christensen’s wardrobe choice. When it comes to person’s actions, only she and her God (if she believes) know their underlying motivations. Shulman wrote that perhaps Christensen “panicked” at the notion of a theme party, “and thought that turning up as the madam in a one-horse town” — yes, a madam — “would fit the bill. But it’s more likely that she did it to show she’s not past it. She’s not going gentle into any good night when it comes to getting her share of the paparazzi’s attention. It’s understandable but unwise.”

Shulman’s whole premise is what’s unwise — and not at all understandable. At least not at face value. So, I’m going to do what I just said no one should — suggest a motive. Shulman is a brilliant editor who, through two decades as the top editor at British Vogue, made it one of the most journalistically and issues-oriented of the Vogue titles. She thus had a major voice in the culture, speaking to and for women. Perhaps she misses the platform and reach that went with that position. Calling out Helena Christiansen for age-inappropriate dressing would surely put her in the center of a social media frenzy. That in turn would put her back where she hasn’t been in a while — at the center of the proverbial cultural conversation, albeit on what most of us would consider its dark side. Maybe that was the plan. As noted at the top of this column, Alexandra Shulman is a smart woman.