"Reef Safe" can mean a lot of things. Most common is "Reef Safe = Fish that do not eat/pick at corals", which a puffer would fall under that category, but another meaning is "Reef Safe = safe for inverts" which is where you will find many fish do not fit that category, like puffers, some wrasses, etc, will eat crabs, snails, and shrimp. I have seen a few reef/coral tanks that had porcupine puffers in them and did just fine.. but obviously no inverts in the tank unless they are meant to be food.