The positive patient was moved elsewhere, one person was released while the man and one other were put into lockdown, he said.
"Nobody told us initially how long it would be. I thought they'd [the Covid positive patient] be the one locked down. It was rather bizarre."
He was told he had been deemed a casual contact and was not tested again at the hospital before being discharged on Monday.
The man said the experience was surreal.
"Nobody knew what they were doing, it was just appalling."
Southern DHB Emergency Co-ordination Centre director Hywel Lloyd confirmed a patient was identified as having Covid-19 as part of routine testing at Southland Hospital.
They had previously been screened as "Green", meaning no risk factors and was asymptomatic, he said.
"The patient was being cared for in a four-bedroom and was immediately isolated into a single negative pressure room."
Lloyd said the patient was asymptomatic, the beds were spaced over 1.5m apart and the ventilation was good through the ward areas.
"Any close exposure between the patient and other patients in the room would have only been fleeting and accordingly they were classified as casual contacts.
"Casual contacts should monitor themselves for symptoms, wear masks when with other people outside the house and socially distance as per advice given to all members of the public. This was relayed to all patients in the room."
He said the other patients were asked to remain in the room and not to mix with the rest of the ward area as a precaution.
"We completely understand the anxiety of the other patients in the room and are sorry for the distress that it has clearly caused.
"Our screening and testing process is designed to reduce the risk to all of our patients and staff and once this case was identified the appropriate steps were taken to try and keep everyone safe."