I’m a bit worried about this one. If Zimmerman succumbs to the temptation to “do the generous thing” and apologise for “the accident”, wouldn’t that leave him open to some sort of “negligent homicide” charge, “reckless use of a deadly weapon” charge , or some such thing? The prosecution (who may be seeing the writing on the wall) may be making a play for a lesser charge like that...
It depends on what you - and how you - apologize for.
I am sorry I had no choice but to defend myself from your son who was pummeling my face and smashing my head into the ground, and trying to get my gun away from me.
You can apologize without admitting you did something wrong. You can apologize for having to do the right thing because you recognize that doing the right thing had negative consequences for others. It’s not required but people can do it. The armed forces routinely is sorry or sends regrets to people about bad things that happened, all the time, without saying what happened was wrong.