Yea, that what I said.
I always suspected Oshus from the start when you see him with Linebeck for the first time before you set out into the sea for the first time. Because he already knew we had the first Sea Chart without anyone telling him that we have it.
In fact, thinking back to the whole whale thing. Its a bit like Link's Awakening when you have the whole thing of being in a dream and at the end it was a Whale. Because it was sorted of like a dream when an the end the pirates said it took only 10 minutes and at the end the Ocean King was a Whale.
They probably just copied it but changed Wind Fish to Ocean King and in the game nothing about meantioning it to be a dream.