I mean Nate of all people should know state realignments across election cycles can be pretty large. Just look at how West Virginia went from a consistent blue state to one of the reddest states in the country in the past two decades.
West Virginia shifted 14 points to Republicans alone between the 2008 and 2012 elections in an election Obama won nationwide comfortably.
Maybe Selzer is wrong this cycle. Polling error isn't correlated across cycles. Maybe it is right and Iowa is shifting even redder. It is also 5 months before the election.