The USSC doesn't have to agree with the 9th or Hiibel to decide that the officer went too far, or that the Nevada law is overbroad.
The Nevada SC did not rule on the case because of jurisditional problems. The USSC now has to decide which jurisdiction is correct. Hiibel is arguing that the 9th is correct and a person has a right to withhold his identity without limits. For example, if one is observed to assault a person, the police can identify the assailant through eyewitnesses and try and convict him without knowing his name. If he had prior convictions, his giving his identity might cause him to receive a more severe sentence and he has a right to not reveal his identity for that reason.