I don't think you read the article. If you had, you'd have seen that McGill (who not a random PT but is the foremost subject matter expert on lower back disorders) is against crunches. It's literally in the title and the first paragraph.
"https://www.macleans.ca/society/health/the-man-who-wants-to-kill-crunches/"
Anything that puts the spine in flexion over and over (or in flexion under load) can lead to back problems.
Instead, McGill advocates the eponymous McGill curl up. You place your hands under the small of your back (to keep the lordosis) and do sort of a plank.
Here he is showing it to Brian Caroll. Caroll was a powerlifter who had herniated discs at both L4-L5 and L5-S1, broken sacrum, multiple endplate fractures and stenosis. He didn't think he'd be pain free again, much less compete. After working with McGill, he went on to deadlift 800lbs and squat 1100lbs without surgery. He's pain free.