Cameo appearance or not, it's still part of the canon. Now, I've never played Black2/White2 so maybe I'd have to see it in context, but it's one thing for them to just get rid of the Rocket guy because he served his purpose (which you are suggesting) and another thing to replace him with an almost identical character (which suggesta a retcon).None of these grunts have a real role to speak of; their cameo appearances only serve to reference the old, now-disbanded teams. Since the Team Rocket grunt served his purpose in Black and White, he was replaced (but not retconned out of existence) in the sequels to avoid repetition. I fail to see how this makes the timeline vague; there are other NPCs in Unova that have left their houses for the sake of change.If they play the exact same role then it does seem kind of like it was retconned. Although it sounds like a pointless one, this wouldn't be the first time they've done so.