Can an autistic 14-year-old develop a new accent?

Hi there! I live in Toronto (Canada) and I'm new to the community. I'm a mom of two, a 7-year-old girl and a 14-year-old high-functioning autistic boy. We moved to Toronto two years ago from Newfoundland, Canada. Our daughter's already developed a Toronto accent so well you wouldn't be able to tell she's actually from Newfoundland. Our son, however, has the same Newfoundland accent he's always had. He's quite socially isolated and doesn't like that he speaks different (he wasn't very socially isolated in Newfoundland). Actually, the Newfoundland accent is much funnier and different in comparison to the other Canadian accents! Me and my husband don't have a problem with it, but our son does. I'm thinking of sending him to an accent coach or buying some standard-American-accent DVD tutorials (the Toronto accent sounds very much like the standard American). The problem is, my son thinks that he'll never actually be able to get the Toronto/American accent, and instead be stuck with a Newfoundland-American accent that he's afraid will sound fake and weird. He definitely doesn't want that!! So my question is, will it be easy for him to develop a new accent? (My husband and I have started developing a Toronto accent ourselves just by staying here, whereas our son still has an extremely strong Newfoundland accent that hasn't changed at all.)