Could you tell me if this "police-procedural-like" situation is realistic in your opinion, or not, and why?

A man is found by the police walking on the street. Alone and without clothes. Searching for fingerprints in the FBI national database, no past, or insolute crimes anyway. But the reiterated refusal to disclose his identity, even in front of a judge, costs him, let’s say, 4 months of imprisonment. I, personally, think, that, even with clothes, that person should’ve necessarily revealed who he was. But, the mere fact that one must go to prison just because doesn’t say his name, is troubling, at least in the USA. Unless, of course, it’s unrealistic. But enough objecting. Let’s hear what you think.