Based on episode 10, I guess Ash's feeling of rejection from Latios seems to have confirmed what being a Pokemon Master means to Ash. Of all the episodes introduced so far within this mini-series, almost every Pokemon Ash has helped has in return accepted him as their friend in which they trust. However, Episode 10 seems to have broken this mold, with Latios rejecting Ash towards the end, even after Ash helped to save it.
Perhaps, the aftermath of the Latios Rescue Story Plot and Ash's resolve after Latios rejected his friendship, gives a subtle message to the true meaning of what a Pokemon Master is to Ash, and that is "A Pokemon Trainer which is accepted by all Pokemon" (The Ultimate Bond Connection), which explains why Ash's goal of wanting to be trainer from the beginning was to build a friendship with all Pokemon, which I guess is absolutely impossible since there are endless amounts of Pokemon around the world, which makes the goal never-ending.
My only conflict with this is that it only supports, the "Gotta Catch'em All" slogan, which is a goal close to Goh's. Despite this, this possible revelation only supports what I speculated before of Ho-oh, figuratively being the symbol of what a Pokemon Master is, since the legendary is essentially depicted in the anime as a creature which all Pokemon accepts as their sacred deity or loyal companion. Its arguably a Pokemon that is accepted by All, which is what Ash essentially wants to have; All Pokemon to accept him as their friend.
If this is correct, then I guess the director of the Pokemon anime was correct in stating in an interview about Ash's goal of becoming a Pokemon Master is truly a silly and childish dream, which I agree.
However, I like the idea of Ho-OH simply meeting with Ash and confirming Ash's resolve of being a Pokemon Master with its acceptance and approval, based on acknowledging the qualities of Ash's character in which he developed throughout his journey by becoming a great trainer factored based on the great connection he has with his Pokemon, which is a trait worthy of being a Pokemon Master, especially since Ash's connection with his Pokemon surpasses most Pokemon trainers which I guess is proven with Ash's victory of being a world champion. The only catch, is that Ash must continue his journey to build that same type of connection with other pokemon, just like how the rainbow bird continues to travel the world in search of good trainers.