He’s probably trying to raise the visibility of this guy getting set free, hoping they’ll reconsider and keep him behind bars.
Afterwards I’d go about my business for a few years, then make my move, if that was my actual intent.
If the dad does kill him, don’t expect juries, the courts, or any government entity to go easy on the guy. The government won’t do it’s duty, but if you try to do it for them, there’ll hell to pay.
The jury might want to help the guy, but their instructions will be so tight that they won’t be able to without endangering themselves.
Good luck dad. You’ve got my blessing.
If I was on the jury or could even get a two letter message to the jury, it would be "OJ", and that would be enough.