They knew - this is obvious to me. They knew it was probably going to get rejected before the league told them. I think Grossman and Lou have been gameplanning this for a few days now (possibly more) and are fully prepared to fight this. They know exactly what moves they want to make.
Well that's good, I think. Provided it's accurate.
Either they know that the NHLPA will file a grievance.
Or they just wanted to give this contract a shot and if it doesn't get accepted in the end, they figured they'd just restructure - which is really not that difficult.