First time I have heard that one. But I have heard of something related.
My guess is the banks will see through this and still go after him. He was the primary and the NOD was filed while his name is on the deed. If he tries to get his name off, they will suspect bank fraud. They won't care if he lived in it or not. And they won't care if they are still together or not.
The best bet is to do a short sale. Otherwise, both are going to have their credit dinged.
Tommy Lee SFR (Short Sale and Foreclosure Certified Realtor)