Nonsense. I'm no D&D lore aficionado but always assumed that Boo is not actually a hamster from space as it's fairly obvious from the outset that Minsc is mentally incapacitated. So, in a sense, it's in keeping with Minsc's character to have such delusional fantasies. In some respects it quite endearing but also fundamentally sad.
Except he is a tribal from a medieval enviourment and Boo isn't a magical, planar or spirit hamster. Boo is a SPACE hamster. The immersion-breaking comes from the fact that a rashemi tribal has a delusion about something that is outside of his character scope. If he was a spelljammer captain it would make sense, but he isn't.
