Perhaps, but it only makes it more heinous if proved that his status as a Vet is what inspired/provoked the attack. I'm presuming that it was his age and weakened physical condition that was more likely the issue at hand.
I disagree. The end result is that an 89 year old, that survived battles in Okinawa died in a parking lot beaten by thugs. The fact they didn't know it makes it no less heinous.
Think of it this way. When caught, they will most likely allege that they meant to beat him only, never kill him. And they may be telling the truth. So does the fact they didn't intend to kill him make the crime less heinous?