Well you could be right idk. But those rings also has meaning for other people so that might be wrong. Just because it might mean the same thing to the public it could mean something different to the strawhats. But the tattoo is also something of a "out of no where-ness" type of thing. And we're not 100% if he did declare a new age for pirates. And if he did i think Rayleigh gave him the idea of doing it that way. Since luffy wouldn't know of it.
Why does Rayleigh care about declaring the new age of pirates?
Answer: he doesn't. Not his intention.