He said "all the talk on the airwaves" about abortion meant his emotions were running high.
The man said he did mention the United Nations in the conversation and said Shaw's laws wouldn't save him before injuring him, which was "stupid of him".
Shaw gave evidence to the court and said the man said "they were coming for him" repeatedly.
Shaw said the man then grabbed him by the lapel and gave him a "pretty solid punch" to his eye, punched him three or four times then pushed him to the ground.
He said he remembers being punch and kicked on the ground.
Defence counsel Marty Robinson asked Shaw whether he "exaggerated" certain aspects of the attack, but Shaw said he was "pretty clear of the chain of events".
However, the man who attacked Shaw said he pushed and tripped him to the ground before punching him twice with his right hand.
He said he didn't kick him or punch him when Shaw was standing up right.
He said Shaw's injuries of a fractured eye socket "were consistent of two punches not multiple punches".
The man said he then walked back to his van and noticed Shaw's glasses were in his hands, so went and gave them back to him.
A witness was walking to work with her husband when she saw Shaw curled on the ground and another man standing over and punching him.
They ran over the pedestrian crossing telling the man to stop.
She said she saw the man punch Shaw at least four times with each hand but didn't see any kicking.
Judge Chris Tuohy reserved his decision for this afternoon.