Questioning Yzerman's roster construction is a different discussion than "Seider bad because analytics".
Three quick points about the useage however:
1. The GM builds the roster, the coach decides how to deploy it.
2. Not sure where you've gotten the impression that the goal is to unlock more offense from Seider.
3. It's a lot easier to find a guy with elite offense like Gostisbehere than it is to find someone with elite defense.
Yeah, which why I said Yzerman's roster construction is bad and that he's a poor GM, and didn't make a criticism of Seider. Regarding your points:
1. Yes, the GM sucks. It's Yzerman's fault the team is bad and Seider is left to get buried.
2. It should be a goal. Seider has the tools to be a truly elite all-around defenseman, like a Heiskanen. IMO, that seems like it would be good for the Wings. Burying him with such brutal deployment, with no help, is not going to maximize him.
3. Even guys like Ghost don't provide "elite offense". Most players viewed this way are just PP merchants, but they don't create much build-up at 5v5 (EDM Tyson Barrie is the canonical example).