Perhaps the comparision is week, but I hike in WDB and Blacktail Rattler county in shorts and shoes all the time.
When I first started going to the Big Bend region of west Texas to hunt snakes, I alway wore hiking boots and often leggings. Now that I live here, I rarely wear anything other than shorts, except on the occassional cold winter days. Granted, rattlers are nocturnal, but I frequently walk up on them in full daylight during the spring and fall. Some give warning, some don't. None have ever struck, unless I tried to move them.
Also, the hunter you mentioned is probably watching the ground very closely for animal "sign". I think it would be unlikely for a sharp-eyed professional hunter to walk up on a snake unaware, unless in high grass (where the snake would be more likely to retreat than strike).