Voltaire.net just posted a 2008 video that may show the real fear his approval generates. In this video, Hagel does two things. First he acknowledges that Israel has nuclear weapons. That's the fact that can't be mentioned in United States politics, at least if you want to be in the main stream. Then, he outlines this "very real" scenario as a danger. The conclusion is, no attacks on Iran, work for peace.
Here is the transcript quotation that may be the source of the trouble. This was recorded on a book tour Hagel did in 2008
"I'll give you a scenario that's very real. If Israel gets backed up enough into a corner and Israel uses a tactical theater nuclear weapon, you want to talk about seeing some things unravel in the world. The United States shouldn't even be thinking about options of bombing Iran or anybody else. I mean we got our hands full right now. And we're in such a hell of a mess." From Voltaire.net, February 11, 2013
Hagel should be approved immediately. For his political oppoents, the only thing worse than his approval would be a rejection of the nomination. Reap the wind, sow the whirlwind as the saying goes. There would be no duck and cover exercise that would stop the storm over this.