I'm pretty sure this topic is about "6th rangers" in name only. It doesn't necessarily mean that there has to be 6 rangers, just an extra character from the starting 5 or 3. And smiling doesn't automatically not make you seem like an ass.
You've read the thread title right, didn't you? Do you know what "6th" means? It is necessary that a sentai has at least 6 regular warriors in order for you to determine if there is a 6th ranger/warrior in it.