Maybe, maybe not. My understanding is that he had a right to be there pursuant to a order of visitation.
One can pickup a child without being on the property, assaulting or battery upon others. You can not use a court order to enable a crime.
He had a right to see his child. If impaired in his right to do so, he had the right to file suit. He had no right to remain on the property when told the child was not there. He had no right to aggressively approach and make contact with the homeowner, threaten to take away the gun and use it on him, and to try to disarm him. He had no right to fling the smaller and lighter homeowner off his porch and into the yard while attempting to disarm him.
He had the ABILITY to inflict death or grave bodily harm to the homeowner.
He had the OPPORTUNITY to inflict death or grave bodily harm to the homeowner.
He demonstrated the INTENT to inflict death or grave bodily harm to the homeowner.
A reasonable person would have been fully justified in being in fear of his life or of great bodily harm, justifying his use of lethal force to stop the threat.
I’d vote to acquit and no argument would convince me to do otherwise. If that hung the jury, so be it.