To me, it's less about whether or not he could hold his own when they started him in the NHL, and more about what would've been better for his development. And at the time and in hindsight, it seemed like a big, gangly teenager like Kotkaniemi probably would've been better served spending another couple of years playing either at home or in the AHL before making the jump to the NHL.
Would've been better for the Habs too from a cap management perspective, since you'd get more out of his ELC years and you'd push back his UFA eligibility into later in his prime.
But I guess when you've got a GM desperate to win now to save his job, long-term planning like that doesn't get taken into consideration.