Thomas Sewell claims he was defending his friend when he attacked the guard outside the Nine Network's building in Melbourne.
The 29-year-old leader of the European Australian Movement faced Melbourne Magistrates Court for a second day on Wednesday, where he contested charges of assault, affray and recklessly causing injury over the March 2021 incident.
He is accused of punching a security guard six times outside Nine Network's headquarters at Docklands, after being denied access to speak to A Current Affair staff about a segment airing that evening.
Sewell, who appeared as a witness, said he visited the network's office with a cameraman after emailing ACA and calling Nine's reception about his right of reply.
"They were going to label us as extremists, that we were the terrorists next door," he told the court.
"There was a chance that they would not give us a right of reply, and that is why we went down with the camera so that we could have a right of reply within our own circles."
After being told to leave the building and film outside, Sewell claimed the security guard began mocking him and his friend, cameraman Jacob Hersant.
Sewell alleged the guard began dancing in a "passive aggressive" way, and then grabbed Mr Hersant by the throat after he told the guard to "dance monkey".
He then laid several punches on the guard, who fell and hit his head on the concrete.
"It was just two quick little punches to try to get him off Jacob. I agree that there are more than two punches, I've realised that since watching the CCTV," he said.
Witnesses told the court they saw Sewell punching the guard while he was on the ground, but he denied this and said they were wrestling each other.
The guard, who has denied touching Mr Hersant, suffered injuries to his head.
Sewell will learn his fate on December 20, with his bail was extended until then.
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