It's probably just an elaborate way of TPCI saying "we don't actually know what Ash's goal is". They say it because it doesn't look good if they don't know some basic information that people would expect after 10+ years. Same with Pikachu. That, or they're trying to create "mystery" where there is none, he's just supposed to defeat a region champion and are making excuses for why the show hasn't mentioned it.
The problem is that, if becoming a Pokemon Master involves beating a Regional Champion, then Ash already achieved that goal by defeating Drake of the Orange Islands, yet that obviously never made him a Pokemon Master. Heck, if we go by the implications about how the Battle Frontier is supposed to be either on the Elite 4/Champion's level, or even stronger than them, and the fact that Ash beat that area, he would have achieved that goal anyways, but he never stopped there, which leads me to believe that beating a Regional Champion =/= a Pokemon Master. If it did, why is Ash continuing to travel?
Heck, they don't seem to even mention the other champions/E4 Members as Pokemon Masters.