If there was not a burglary going on, this would have deserved a ban, but you did interrupt a clearly (attempted) stealthy raid, and it looked like Boyle was involved with that.
There are a few issues with this on your side:
1: You probably shouldn't have tried to interrupt a burglar, you should have called the police.
2: Boyle may have killed you because there was a medic nearby, and you could have told him, in which the medic would instantly get the police there.
3: Boyle may have killed you just out of instinct, I realize this isn't your fault, but raids can be a very stressful and paranoia-filled time, and Boyle may have just killed you in the heat of the moment, it would have been different if you had told the burglar to stop, and then Boyle had killed you after you talked to him, but the whole thing happened in a 10 second time frame, and from Boyle's point of view, he just saw a guy standing really close to his (potential) raiding partner.
Now there are more severe issues on Boyle's side:
1: He shot you with a high power shotgun in a highly-populated area, near a medic, he would have heard.
2: He didn't seem to have a valid way of escape after he had killed you.
3: If he wasn't involved in that raid, he'll be in big trouble.
Overall, I can't really make a decision, as the entire video is a bit vague, we really need to hear
@Sdac2 's point of view on this.
If he was involved in the raid, I would say a day's ban (depending on how many past bans and warnings he may have).
If he wasn't I would say a week (Once again, more would be appropriate if he has recent past bans or warnings).