Prime Minister John Key accused the Opposition of backing "rapists" in the debate over conditions on the small Indian Ocean island.
His comments triggered an unusual walk-out in Parliament, as several MPs voiced disgust at the comments.
Today, Mr MacDonald dismissed suggestions Kiwis detained in Australia were hard done by, or detained for minor offences.
"We're dealing with very serious criminals. These aren't visa miscreants."
He said 27 of those in detention had committed assault, five were guilty of child sex offences, 27 had drug convictions, nine had grievous bodily harm convictions, two were guilty of manslaughter, and nine had theft, robbery, or burglary convictions.
The senator said the sooner Kiwi detainees were out of Australia, the better.
"If people have rejected the hospitality they've been given in Australia, then all bets are off and they should go back to where they came from."
The Nation said Mr MacDonald, a senator from Queensland, was chair of the federal committee that approved immigration policy changes affecting thousands of New Zealanders.
A law change in Australia meant the Minister of Immigration could revoke the visas of foreign-born nationals on character grounds.
Some of those now detained had been in Australia since childhood, yet were still at risk of deportation, even if they had no family or friends in New Zealand.
Mr MacDonald told TV3 Kiwi detainees who'd been in Australia since childhood should have by now applied for Australian citizenship.
Mr MacDonald said he wasn't aware of Ko Haapu's case.
Mr Haapu, a former soldier who once acted as a personal bodyguard for John Key, had his visa revoked on the grounds he belonged to a a motorcycle club.
The former lance corporal was now in Casuarina maximum-security prison in Perth.
"He would have been more than just an innocent bystander in a bikie gang," Mr MacDonald claimed.
"If he's done all of those wonderful things in New Zealand, you'd want to welcome him back."
Mr MacDonald told The Nation he would be very surprised if anybody was deported for minor offences such as shoplifting or decades-old cannabis use convictions.
"You give me a case where someone has been deported because of a shoplifting or a 20-year-old cannabis offence."
But he added: "Let me know and I'll see what I can do to help them."
Maori Party co-leader Marama Fox said some of the senator's comments displayed a breathtaking lack of awareness.
Ms Fox said there was abundant evidence Kiwis were "being held in detention centres for minor crimes" despite what Mr MacDonald said.
"It just defies belief the things that this man is saying," she told The Nation. "He is absolutely ignorant."
Ms Fox said she knew of a Kiwi aged 60, who lived in Australia for 36 years, came back to New Zealand, and was denied re-entry to Australia because of a conviction for theft entered more than thirty years ago.
She said this man was now unable to appeal his deportation back to New Zealand.
Ms Fox dismissed the senator's claims about Mr Haapu and said Australia's new laws were draconian.
"They have given the minister absolute power above the law to determine whether somebody has their citizenship revoked."
Ms Fox said people seeking help with detained loved ones had already received hollow promises of help from New Zealand authorities.
"People are struggling to find a direction here to know what to do."
