But Dont Ask Dont Tell had nothing to do with having sex. The policy was about talking about sex. Soldiers having sex (straight or gay) while on duty isn't allowed. So is Santorum saying that straight soldiers shouldn't be allowed to talk about their wives and girlfriends and which celebrities they would like to bang? Because that is what DADT demands for gay soldiers.
It's the same as when Romney and Cain talk about "Obamacare." Romney says that his reforms in Massachusetts are different because they don't "put someone between you and your doctor." Cain says that he doesn't know if he'd have survived cancer under the current reforms. It's a slightly more civilized but equally false variation on the "death panels" claim. When most of the Republican candidates (or, for that matter, most elected Republicans) talk about Obamacare. they're referring to something that has only a very loose - and largely coincidental - resemblance to actual policy.
I think the that best way to understand Santorum's argument apropos DADA is to view it in the same way. It doesn't matter what the actual policy is, because it's
Obama's policy. So he makes it sound as threatening as possible, without any regard for facts.