The debt, if it is as described, is indeed time bared. However if it is a valid debt they can still try to collect it. They are allowed to contact you and request payment if they do own the debt even though time bared. The SOL being past simply removes the option of them suing you and winning (provided you show up and use the SOL defense). Paying anything on this debt now would serve only to reset the SOL.
The FCRA comes into play here as well. It is beyond reporting to the CRA's. All that means to collection activity is that they can not place it in your file, not that they can not try to collect it. They are still bound by the DV, so they must stop collection activities until it is validated (which can still happen).
Should they actually validate a debt that old they can continue to attempt to collect as long as they stay within the FCRA in their attempts. That means that they can send you letters and call until you tell them to stop. Once you tell them to stop they can resell the debt and it can start over again.
What this all means is that while they can not really force her to pay this debt they can try to collect. If you enforce your rights then they can simply include it in their next portfolio sale and someone else can attempt to collect it.
The things we do even many years ago can and do still affect our lives. Debt doesn't simply go away, it just becomes harder and harder to collect. And the system is set up in such a way that if you really wanted to do the right thing it would come around and bite you right in the behind.
If it were my debt the first thing that would come to my mind is, well lets get it paid. However simply by doing the right thing what would happen is all of a sudden a very old debt that I have already paid the price for not paying would come back to haunt me. As soon as I paid it the SOL would be reset (even though it would be paid in full and wouldn't exist anymore), and someone somewhere would decide that it should be reflected on my reports (either through maliciousness, or ignorance) and I'd have to deal with that.
So having said all of that I probably didn't really answer your original question, but it did give me an opportunity to vent on the system that punishes you for doing the right thing.
Personally I'd pay the darn thing off simply because I owe it however she probably should leave it alone and keep an eye on her credit reports to make sure some CA doesn't attempt to place it on there in an illegal attempt to force her to pay it.
Thanks for letting me rant.
Van