I actually agree with you in that if your going to take Seattle on the ML, this is the way to do it. Seattle simply doesn't have the offensive production to blow out the best offense in the NFL by more than 10 points
Threads like this explain why Vegas cleans up. I'm on Den and even I think Seattle could easily win by two TD's if Manning doesn't show up. Something like 31-17 seems like it could easily happen. Just take the plus-money moneyline if you're on Seattle don't get cute.