Holmgren left the field so he could whine and fit in with the rest of the whiny lefties up there in the Pacifistic Northwest.
He'd much rather blame the zebras then talk about missed field goals, blown defensive assignments, dropped passes, and mismanaging the time clock. The Seahawks linemen were tackling Steelers all day, Hasselbeck nearly missed Taylor on the tackle and ended up nearly cutting the legs out from under Carter - that's why he got called. Don't want pass interference on offense? Don't lock your elbow when you push off to create space.
Holmgren is basically saying "we lost 'cause the refs won't let us cheat."
Winners make plays and losers make excuses.