I agree with you that the requirements for permanent safe storage are very high - thousands of years with no leak, besides others - but nonetheless, even with simpler requirements, Yucca - or any other georep - was not deemed safe.
Mostly NIMBY problems that apply for the repository apply for transportation, but in lesser scale. Yucca was not as dry or geological stable as initially thought, and the requirements for "permanent" disposal are very stringent, so Yucca is not considered anymore for long-term storage.
It depends on what you define as long-term. For a few decades, with proper inspections, sure. For the geological time frames needed for nuclear waste disposal, definitely not.