If someone had just arrived here in a time machine from 5 years ago, they'd be posting "Who the heck thought that Santorum would have a chance at even coming remotely close to winning a state in a Presidential campaign?"
Anyways, as the runner up from the previous competitive primary, he'd normally get it this time, but the except seems to be if your daddy was President, so that means Jeb gets it.
It's not that Republicans automatically nominate alsorans, but that alsorans have an advantage in name recognition and fundraising.
Santorum was second place in one of the weakest fields in the party's history. He makes a really weak argument that he should automatically have been granted admission to the main debate because he won Iowa, but I'd argue it's the other way around. If he won Iowa and he's polling so badly, his numbers aren't going to get better.
He would probably be better off dropping out, and playing socially conservative kingmaker.