The Wings cant say they knew about it. If they admit they dealt a player that was definitely bolting they would be sanctioned by the league for not negotiating in good faith. It would also prevent other teams from ever trusting the Wings in any deals from then on. They will never admit they knew anything.
Uh, if he had a deal on the table with SEL every team would have known about it, the IIHF has a transfer agreement for this very reason.