Yes, I agree with you, the fact that Santorum comes from a working class background and actually did some hard work as a young man helps his case a bit. Just imagine how much more his case would be helped had he bothered to serve a tour in the armed forces...
FWIW, Santorum’s father was a veteran and a career VA psychologist who went to school on the GI Bill, and Santorum served on the Senate Armed Services Committee. That's about as close as you can get without wearing the uniform.
I'm originally from Grand Rapids and I am very happy to see this development with Santorum. Romney has three problems: social conservatives in West Michigan, blue collar Reagan Democrats in the Detroit suburbs, and an attitude outside metro Detroit of detestation for that city and what it represents.
Growing up in Grand Rapids, I remember people having bumper stickers on their cars saying “secede from Detroit.” Detroit's power has greatly diminished over the years, but being a metro Detroiter is no more of an advantage outside metro Detroit than being a New York City resident is outside metro NYC.