Ahhh... so he refused to take any crap from the elders!
Yep, I agree with that. His son is a boxer. Boxing used to be a DFing offense. It may have changed, but not all elders get the memos, if you know what I mean. The son isn't a baptized JW maybe, but the father, taking an active part in his son's career has probably gotten the elders all hot and bothered about it. I could see the elders telling the father that he could not have an active part in his son's career as it is against the rules. Father says FU and thus the elders declare him DAd on the "brazen, defiant attitude" clause.