I guess the " scooping " motion ad the bottom of the aft empennage contacted water can cause the fuselage to rip apart. Had the outflow valve been close, it would have sealed off the hole and reduced resistance which cause the bottom aft fuselage to rip. Also the ditching switch closes other apertures as well. I must agree, the Americans love heroes and are definitely not going to take this one down like BA did to Captain Burkill. Remember, they also manufacture heroes and heroines out of Iraq and Afghanistan.
With the incident caught on tape and no loss of life, Sully is indeed the perfect poster boy! And deservedly so!