Keep in mind he did have chainmail, which was 4 pts of armor. Also, keep in mind, that he might not have felt the hits because of the chainmail. I saw a few there that I would have taken unarmored as I ran by, that were very close to grazes. Any armor, leather or other, can take a lot of the OOMF out of shots, and turn run by shots like that (when he's running by and someone's reaching for him) into feeling like a graze.
Alternatively, yes, he could have been ignoring hits, because by that point I think he had gotten ticked off about an armor issue with another fighter. I really don't know, but I also don't think that any of us should be starting the cycle of calling others sluffers and rhinohiders. It just builds up to more drama. Fight, have fun, ignore people not taking their hits, and just hit em harder. Granted, in Amtgard, we can't slam em down and beat on em if they do sluff. BUT, we can definitely hit harder and harder, and if need be, pick up heavier weapons and hit ever harder, if it comes to it.
Also, I would advise either talking to the fighter, or to the person running the practice about it. Bringing it here won't really do anything, cuz I don't have any influence in Amtgard.