I disagree (although there ia an exception that I will address).
Let’s look at the math in this. Most proportional States have certain rules about who gains delegates and in which way. For example, a lot of States have a rule that you must hit the 20% threshold in order to gain delegates, and you win bonus delegates by winning Congressional districts.
So let’s look at Alabama last night.
Last night:
Santorum 35% — 17 delegates
Gingrich 29% — 12 delegates
Romney 29% — 10 delegates
Now if Gingrich wasn’t in last night, we would like to assume that all of his votes would go to Santorum, but likely some would go to Romney. If as little as 12% of Gingrich’s vote total had gone to Romney, the results might have looked like:
Santorum 59% — 27 delegates
Romney 34% — 12 delegates
Now if you are hoping for Santorum to win the nomination, that is a better outcome. But the odds are very long that Santorum will win the nomination. If your goal, however, is to stalemate Romney and deny him the nomination, Gingrich dropping out would be a bad thing because it would allow Romney the chance to build more delegates.
Now, the exception is that I believe Gingrich should pull all efforts from any “winner take all” State and work behind the scenes to push Santorum forward. Texas and Illinois could both fall to Santorum if Gingrich would do that, and that would seriously hamper Romney.
Actually, many states such as both Alabama and Mississippi become winner takes all if a candidate can get above 50%. In your scenario, Santorum would have swept all 47 of Alabama’s delagates and Romney would have been blanked.
Furthermore, in my state of IL, people will vote for Newt if he is in the race. In a poll on Sunday by the Chicago Tribune, Mitt had 35%, Rick had 31% and Newt had 12%. Newt is still attracting votes here, and Newt is coming to Chicago today, so it is not hard to see why.