He has a moderately good chin but his last two opponents were Bundu and Guerrero. He never really took a proper timed clean shot to the chin so who knows. Bundu is more of a accumulative puncher who is borderline or pillow puncher. Guerrero is a wild aggressive type who might not catch you completely clean but land.
It's the one box that still needs ticking for me. That sour old charmless creep Virgin Hunter said Thurman better watch his chin because he knows some things about him that haven't come to light yet but will do at some point.
for some reason I don't think it's iron, I remember Sotto Karras visibly rocked him at the beginning of their fight
