Without knowing what kind of assault was going on, it's difficult to say whether the employee's actions went overboard or not.
I think one reason we have more crime than we should is because of companies like this insurance company. There was a story not long ago about a pizza parlor hold-up where just after closing, an employee leaving the store was forced back inside at gunpoint for the heist. During the robbery, believing the robbers would kill him and the manager, he grabbed one robber's gun and was shot in the stomach. The insurance company claimed he was "on his own time" because he'd punched out. This kind of weasel-mindedness to preserve profits while ignoring the moral imperative to preserve one's own life and/or stop crime is disgusting.
I'm not saying the insurance companies should always indemnify people for playing the hero. But if the "domestic violence" incident involved repeated blows, I think they should have paid out the claim. If nothing else, it sets a community expectation that such behavior isn't tolerated in that town.
I'd like to know if the insurance company is claiming that the employee "voluntarily" put himself in harms way, doing something not required of him, and thus isn't eligible. Would they also not pay him for his injuries if a coworker's clothing caught fire and he "voluntarily" helped beat out the flames? I think not. Would they not pay the claim if he tackled the same man for assaulting a female employee sweeping the floor?
The lawyers for this insurance company (and arguably the insurance company executives), IMO, show their contempt for any moral values whatsoever.
BillCA in CA (Unfortunately)