I think there is a period of time between when someone passes BUD/S and the time they are officially a SEAL. So this guy could be a legit BUD/S grad and not have fully earned his Trident yet.
Or yeah, he could be a complete poser.
One of our resident SEAL or SWCC guys would know best, but my understanding was that you're not a SEAL until after SQT which follows the end of BUD/S. Meaning he may have completed BUD/S, but is still a SEAL trainee.