My kids daycare has the following classes: infants, crawlers, toddlers, 2 year olds, 3 year olds, 4 year olds. They don't ask which one you feel like you are, you clearly fit in one, or you don't.
The notion that they would allow some idiot to join because he "identifies" as a 4 year old is no different than expecting to be allowed to go sleep in a kennel at the vet clinic because he thinks he's a Labrador retriever
I get what you're trying to do with your analogy, you're just taking it to such an extreme that it loses its relevance
