Ryan Potter (born September 12, 1995) is an American actor and martial artist. Beginning his career as a professional actor at the age of 15, Potter is perhaps best known for his starring role as Mike Fukanaga in "Supah Ninjas" and for voicing Hiro Hamada in "Big Hero 6" (2014).
Ryan Potter was 19 years old when he voiced his character in "Big Hero 6".
Big Hero 6 was released 19 years after Ryan Potter's birth year, but it's not clear how old he was when he did his voicework for the film.  Thus, the statement is neither correct nor incorrect.  I assume the agent has trouble with doing math, or knowing that films are prepared in advance of their release, and that's why it got this wrong.