Sources suggest Iger already has given up on his political aspirations. He simply didn't come across as likeable to ordinary folk.
Likeability is an extremely important characteristic for a politician. In the United States in contested districts, the more likeable candidate usually wins.
Think of it this way. Republicans are highly likely to vote Republican. Democrats are highly likely to vote Democratic. The middle ground usually is left with 2 candidates who they agree with on some issues and disagree with on other issues. Inevitably, they end up voting for the candidate who seems more friendly, more likeable.
The same holds true for party nominations. All party candidates support most of the party platform. What distinguishes them is likeability.
There's a reason Iger extended his reign as CEO through June 2016. Iger will be 65 by then, rather late to start a political career.
Besides, given recent price increases, Iger already comes off as an "evil money-grubbing capitalist pig overlord ".