How does Jack know that the man who rescued him from the coyote hole was a road agent?

Jack recognizes the man who rescued him as a road agent by his distinctive clothing and gear, which are characteristic of those who travel the roads and protect travelers. The man's demeanor and authority also suggest he is part of a organized group tasked with maintaining safety in the area. Additionally, Jack might recall hearing about road agents from others, which further informs his understanding of the man's identity.