Despite searching on PubMed using iPubMed from UC Irvine and browsing around using "Related Links", I can't find anything about Social Stories and teenagers, young adults, or adults. Someone with journal access can take a look at http://www.ncbi.nlm.nih.gov/pubmed/22284800 to confirm/disprove my suspicion.

The stuff I could find is quite uncertain about how helpful Social Stories are but there are no reports of harm so if a TV show can sneak in Autism Spectrum Disorder treatment, even if it isn't super effective, that's terrific. It can be difficult for older people to get a diagnosis and good evidence-based treatment; if My Little Pony can help that population for low to little cost, I'm all for it.