Kim said he was worried about the living conditions, and had not been able to contact his wife - who is 6-months pregnant and had travelled with their 2-year-old daughter.
"They are staying in a van and probably share common facilities like showers," Kim said.
"I am not sure even whether they have power to charge their phones, or if they are being treated like a member of the army."
Kim said the last time he heard from his wife was before midnight, and "worried a lot about her and baby's situation".
A Ministry of Health spokesman said a team on site had met with Gao to help assist her.
"We're sorry to hear about this stressful situation for Mr Kim and Ms Gao and we want to reassure them that everything is being done to support people at the Whangaparāoa Reception Centre as well as their loved ones who may be elsewhere," he said.
"It's very important people are able to stay in touch with their loved ones and we fully support and encourage them to do so. Staff at the site are working to help them reconnect."
He confirmed returnees are being provided a recreational vehicle (RV) per family, group or individual to offer them a private space of their own.
"Returnees are not being kept in the RVs and can move around the base area and enjoy the facilities," the spokesman said.
"They are not being kept from being in contact with each other, but there are appropriate health precautions in place such as wearing face masks, and all who are on site receive regular health checks."
So far no one at the base has exhibited symptoms of any illness.
"It's important to emphasise these are healthy people who are being isolated for 14 days," the spokesman added.
The was chosen due to its size, location and access to medical facilities, and evacuees will receive daily medical checks while in isolation.