We know that viable viral particles can survive in the air. For them to remain viable in a pocket of air is not an unreasonable assumption. It's not like they are going to use all of that air and suffocate. So it's a matter of can they remain viable in the time between when that pocket of air is sealed and when it's unsealed. Since the highest length of viability I've seen is 72 hours, my assessment is breathing the air from one of those plastic air bags used in shipping is less dangerous than handling the exterior box it came in.