I like many here want to stop Romney from getting the nomination its that simple. Folks that want Romney want Newt to drop out, again a simple concept.
Given the current poll numbers, Newt is playing the Ross Perot spoiler role in this state. He's handing Romney the win. If he dropped out and his votes went to Santorum, Santorum would win. This is simple math. Your assertion that Newt dropping out helps Romney makes no sense in at least this state.
If I lived in Illinois I'd vote for Santorum and I'd encourage other Newt supporters to do the same. Looking at the national numbers the only way to prevent Romney from getting the nomination is for both to stay in and conservatives in the individual states to support whichever has the best chance of beating Romney in that particular state.