At 7pm the marketing student slipped between the bars of his "presidential prison" to oppose the Education (Freedom of Association) Amendment Bill, sponsored by Act New Zealand MP Heather Roy.
However before beginning his self-imposed two-day incarceration he was involved in an altercation with a member of Act's campus branch.
Mr Edgar said an unknown Act member was brandishing a sign with "I love Liberty" while a group of vocal opponents tried to "hijack my campaign".
"I screwed it up, threw it at his feet and he stepped up and grabbed me by my throat."
Mr Edgar alleged the man also threatened to punch him.
Last night he was unsure whether he would lay a complaint with police over the incident.
"It makes Act look like thugs," he said.
Act on Campus Otago president John Brinsley-Pirie confirmed a member of the party was involved in an altercation with Mr Edgar.
"It did get a bit tense."
Mr Brinsley-Pirie said he did not see the party member grab Mr Edgar by the throat, or threaten to punch him, and the members were not trying to be confrontational.
"We told him that this was a very regrettable circumstance."
Mr Edgar said he would rather debate the issue with Mrs Roy, and invited her inside his cage, after the Act tertiary education spokeswoman accused him of being "bored".
"His planned protest makes the opposite point to what he presumably intends," Mrs Roy said.
"Voluntary student membership will free students from the cage of student associations. It won't lock anyone in or out - as Mr Edgar is claiming."
