As a player you need to protect yourself, it's arguably one of the most important skills to teach young players.
Especially as a d-man when you're retrieving pucks from the corners, which is a standard play you're making shift in and shift out. Your head should be on a swivel making sure you're aware of forecheckers. Many times it's smart to iniate contact instead of waiting to get hit. If you're a smaller d-man likely to get outmuscled, use deception and skating to get out of trouble. At all times - be prepared to get hit.
Looking at this hit, if McIsaac is even a little bit prepared it would be a nothing play. It's possible Jared isn't feeling confident absorbing a hit shoulder to shoulder after his surgeries. But if that's what causes him to instead put himself in vulnerable positions it's obviously a massive issue.
I'm thinking along similar lines.
The way I'd explain it: freeze
the video as the forechecker is crossing the goal line and study the situation there.
His job is to move quickly with McIsaac and try to cut him off, depending on which way McIsaac turns. The forechecker doesn't know which way McIsaac is going, and we all accept that defensemen are supposed to try and make quick turns and fake their way into some open ice.
Instead McIsaac doesn't turn, and we'd normally call the alternative option "choosing to take a hit". But instead of doing that, McIsaac just stops, facing the boards, and lowers himself down. Keep in mind, he's actually four inches taller than Malatesta here, but he makes himself look tiny. I can't get in his brain here, perhaps he's doing what many defensemen do these days and turning his numbers towards the attacker to ward off the hit (because it makes the hit illegal), or perhaps he's subconsciously protecting his repaired shoulders by not turning.
And I'm not sure what else we're seriously asking Malatesta to do there. Obviously we would want him to let up if at all possible, but we have to remember that he doesn't know where McIsaac is going until the second he runs into him. Malatesta doesn't extend through McIsaac. You can't ask a forechecker to pursue more slowly just in case the defender puts himself in a bad position.