He's used those two and he gets his hands on the keys for a whole lot of extra heroes from Basco even if he doesn't use em in the show. But here's my reasoning: That's kinda boring. Sixths and extra heroes aren't the same thing, and while having them all in one character was probably more comfortable for the show makers it doesn't mean that it's the best course of action, particularly for a roleplay that already deviates from canon. Not to mention Gokai Silver uses those two extra hero keys compared to 14 sixth ranger keys, which I feel puts him rather firmly in the sixth ranger ground. Hell Gokai Silver can keep the extra heroes keys if you guys want, I'm not even a huge fan of a million forms gimmick. I can work this into my character by giving him an attitude about having to rely on other people's powers instead of your own.