What’s unrealistic about Horowitz or what he had to say?
There was/is a sequence that you have to recognize.
When the conflict in Libya arose, the NeoCons in the GOP immediately began criticizing Obama saying that he should intervene. The NeoCons felt safe doing this because the Realists have great influence over Obama's foreign policy and the Realists wouldn't allow Obama to intervene.
But, then, the Liberal Interventionists in the Dem party joined the NeoCons in the GOP and called for Obama to intervene. So Obama intervened.
Now the NeoCons have to walk it back. Change their position, for partisan reasons. They originally criticized Obama for not intervening and now they are criticizing him for intervening.
Sullivan's response to Horowitz's original piece was ridicule and Horowitz's second piece was an attempt to deflect the ridicule by claiming to be a Realist. And of course, Horowitz pulled the NeoCon whipping boy bogeyman, George Soros.