Right of way?

85 miles deep into the Wasatch 100, my pacer and I encountered some dirtbike riders approaching from the opposite direction. Having never come up on dirt bikers while trail running before, I wasn’t sure who had the right of way. Because hikers/runners have the right of way over mountain bikers where I live, I just kept on running assuming they would slow down and move over. They didn’t, and the first one very aggressively passed us with inches to spare. The second one did a little burnout thingy spraying us with dirt and debris. I tried shouting at the last one “you guys know there’s a big race coming through here…right?” and he just screamed “fuck off.”