Police arrested Te Aho a short time later and he apologised, saying he shouldn't have said it. He pleaded guilty to behaving threateningly.
Defence lawyer Raukawa Simon said Te Aho was actually seeking a grant for travel to Wellington, where he was about to have eye surgery.
Te Aho told Judge David Cameron the comment he made arose from stress, as he didn't know if he would get the money to go to the operation, and did not know if he would die during surgery or become blind.
He said he "just had a personal korero" with the security guard, whom he had known for a long time, and the comment was "just blown up out of context".
"I'm not a bad person ... I was stressed that day, that's all this was.
"I apologise deeply from the bottom of my heart for what a stupid comment I made."
But Judge Cameron said the threat was "more than a stupid comment".
"It was threatening behaviour and it's totally inappropriate," he said.
He sentenced Te Aho to 40 hours of community work.