Sounds like the Pro-IT T1, Lap 1 at Road Atlanta a few weeks ago...

I'd say that you're prefectly fine passing these cars as they were involved in the melee in some capacity. Although they may not have had metal to metal contact, they ended up off the race surface and have lost race pace. My understanding has always been that the "no passing under yellow" rule was directed more towards executing position improving passes on the race surface. Your scenario is a bit different and not all that uncommon on race starts.

Christian