I've never seen Ranger Johnson in that full outfit before. I've met him several times and even talked to him about his side project.
He's done that interpretive work before visiting schools and museums over California. I think he's also won several awards as a result.
I did see a ranger walk and talk on Buffalo Soldiers at the Presidio of San Francisco - hosted by Rik Penn of GGNRA. The content included video of Ranger Johnson at one of the museum events he did in Oakland (I think) as well as descriptions of the ride from San Francisco to the Sierra.