It's weird that's always been left so vague. I wonder what exactly it is at Lodestar that gives you the poneglyph hint? Surely it'd be on the WG's shit list too?
I always thought it would be a special poneglyph on Rodestar but that does end up being a bit circular. If you don't already know how to read them and didn't think of them as important I don't know why a poneglyph itself would change your mind.
Definitely a strange issue as far as WG is concerned. It's clearly a reachable island so why they haven't just destroyed it or better yet built a base there to keep it under their control is beyond me. Like before the great age of pirates was the New World even hard to control, and if so why?