One of them, a woman, died earlier this week.
The 56-year-old Butler had been holidaying with his partner, Robin Russ, who remains in isolation.
“I tested negative and he tested positive,” Russ said over the telephone from the apartment they moved to for quarantine.
After disembarking at Sydney Harbour on March 19, the couple journeyed home – including on public transport – to the town of Tamworth, some 400 km (250 miles) north.
Butler developed a “funny cough” the next day and soon tested positive, said Russ. Days later he fainted and was taken to hospital by ambulance.
Health authorities had classed the Ruby Princess as low risk, given it had sailed from Sydney to New Zealand, and the Border Force issued a notice instructing the 2,700 passengers that they could travel home in the normal manner, but should self-isolate for 14 days.
Like the Diamond Princess, the liner held in quarantine off Japan last month, and the Grand Princess which was denied entry to its home port of California earlier this month, the Ruby Princess is owned by a unit of Carnival Corp, the world’s largest cruise operator.
The incident has sparked outrage among Australians who have questioned why those on board were permitted to disembark, and federal and state officials have clashed over who is to blame.
“If we had known we would not have gotten off the boat,” said Russ. “Why would they let you off and put so many lives in jeopardy? People have gone all over the world.”
“People are saying ‘we hope you die’,” she said.
According to Russ, passengers saw a woman being carried out by stretcher from the Ruby Princess before dawn on March 19.
“That’s when we all started panicking,” she said.
Passengers who spoke to Reuters said they were suspicious about the speed they were rushed off the ship, with “no checks” of bags or passports by officials.
Princess Cruises parent company Carnival Australia said in a statement on Wednesday it complied with protocols and it was most likely “the illness was introduced unwittingly to the ship following embarkation in Sydney”, on March 8.
After stepping off the Ruby Princess, Butler and Russ travelled on public transport to Sydney’s Central station where they took a train to the coastal town of Tuggerah and then completed their journey by car.
Another couple who flew from Sydney to Darwin have since tested positive for coronavirus, while an American woman and her husband caught a flight to San Francisco.
On Wednesday, Australia’s Border Force Commissioner said the New South Wales (NSW) health department bore responsibility, and that it had been notified by the ship’s doctor of 13 passengers with flu-like symptoms who had been isolated.