Getting a longer duration in Place or any obedience command for that matter can be accomplished with "punishment for non-compliance of a known command", especially if you are trying to get a dog to be nice and calm. You can absolutely use whatever motivator you want to teach a behavior. When your dog understands what you want, its time to add a consequence/punisher for breaking the command. It is fair as long as you also teach the dog what the punisher means and what to do after you apply the punisher.