"Actually, that's one of the things I was thinking about writing a story about me, loosely based or autobiographical. I just don't want to be like some people that are in their twenties and writing autobiographies"

Matthew McGrory is suggesting that he wants to compose a story about himself, however he does not want to resemble some people in their twenties who write autobiographies. He is suggesting that he does not want to be viewed as someone who is too young to be blogging about their life experiences. He is recommending that he wants to write a story that is loosely based upon his life, however not an autobiography. He is likely attempting to prevent the stigma of being too young to write an autobiography, and instead wants to compose a story that is influenced by his life. By doing this, he can still inform his story without being viewed as too young to be discussing his life.