I guess it all depends on what you're looking for for a final product. If you're looking for "fall off the bone" texture, then holding them at 140˚ or above should work for a few hours. However, unlike something like a brisket or pork butt, ribs don't have the mass to hold heat for all that long. The preheated cooler/towel trick will work for a while, but it's no guarantee.
If it were me, I'd follow this advice:
"My plan is to pull them at 10, let cool, pack into foil pan, double wrap, the in the cooler with them on ice. Then reheat on hot grill and apply bbq sauce."
In other words, you had the right idea the first time. I don't know what temps you're smoking at, but 5 hours should get the ribs pretty close to the "tender but with a bit of pull" style that I happen to prefer. A quick chill and reheat on a grill will maintain that for an indefinite period of time. Once chilled, there's nothing happening to the ribs, so any delays you might experience won't cause a problem. If you were trying to hold them hot, the clock is ticking the whole time. In addition to safety concerns, the meat is also continuing to break down the whole time. For my money, I'd rather be able to relax and know the food's happily on ice and will be ready for a reheat whenever needed.