Martha Stewart is not going gentle into that good night. In her case, raging against the dying of the light entails sporting a swimsuit on the cover of Sports Illustrated. At 81, she’s the oldest ever to do it. So much for the dignity and wisdom that comes with age.

In the description of the New York Post, she “models a plunging white Monday Swimwear one-piece ($192) along with a billowing orange cover-up by Torso Creations on the front of the iconic glossy.” Even better: “Stewart showed off a bouncy blowout and dewy makeup look for her shoot, looking decades younger than her actual age.”

Which brings up a question: What’s the point? Why the Halloween costume? The Post has an entirely separate story about how she prepared, saying “she got serious about her diet and exercise routine ahead of her shoot.”

“I didn’t starve myself, but I didn’t eat any bread or pasta for a couple of months,” Stewart shared during an appearance on the “Today” show Monday, per People.

And she did Pilates. Good on her, but the narcissism/exhibitionism just seems a little, well, tacky.

The thirst trap queen previously shared some of her tips for looking fabulous in selfies with Page Six Style, telling us she starts every day with her own homemade green juice and makes sure to “project” her chin and “optimize” lighting for the best results.

Kind of funny: I’m undoubtedly showing my age when I admit I had to look up “thirst trap,” because the first time I came across it was in a story about an octogenarian.

Despite prepping with extra exercise and a stricter eating plan, Stewart isn’t all that interested in anti-aging treatments.

“I think all of us should think about good living, successfully living, and not aging. The whole aging thing is so boring. You know what I mean?” she said on “Today.”

Well, she’s not all that interested in admitting she’s interested in anti-aging treatments. The lady doth protest too much about this stuff:

“When I heard that I was going to be on the cover of Sports Illustrated Swimsuit, I thought, ‘Oh, that’s pretty good, I’m going to be the oldest person I think ever on a cover of Sports Illustrated,’” she told the magazine, adding, “And I don’t think about age very much, but I thought that this is kind of historic.”

Not really. It’s part of a trend of old people behaving badly. At 79, Robert DeNiro just fathered his seventh child. That’s amazingly selfish.

At 85, Jane Fonda is out there protesting climate change like the young communist she once was. You’d think at some point you’d say, “I’ve had a long career screwing up my country, it’s time for a well-earned rest.” Professionally, she’s no better. “80 for Brady” is conceptually cringe-inducing (I haven’t seen it. Surprise!), as was “Grace and Frankie.”

But this is the Viagra Generation. Yes, in these days of sexual assertiveness we’re supposed to be supportive of everyone letting their freak flag fly, no matter how ill-advised. It would be regressive and puritan to do otherwise. You don’t want to be accused of slut-shaming Grandma.

SI, of course, does the swimsuit issue to generate buzz (I don’t know if they have any dudes in bikinis this year, or if that was a one-time thing). But part of the swimsuit issue’s appeal was the fantasy of walking down a deserted beach in an exotic location and coming across impossibly beautiful women being impossibly sultry in impossibly small bathing suits. It’s not the nightmare of walking into the backyard and finding your Aunt Edna recreating the pinup-girl poses bomber crews painted on their B-17s.

What’s wrong with being a grand dame? An elder statesman? I guess I’m an old fuddy-duddy. But at least I know it.