She is now staying in a police safe house because of fears to her safety, after alleging being threatened by Sroubek.
She has written to National MP and justice spokesman Mark Mitchell, giving him permission to speak for her, and Mitchell has questioned why Immigration NZ officials turned up at the safe house to "pressure her" into taking part in the review.
Mitchell said no one should have known where she was except the police, and Immigration NZ turning up without notice amounted to "bullying behaviour from the state".
Nash agreed that only police should know her whereabouts.
"There are some people who just need to be kept safe, and there's no way anyone apart from police should know where that is. I'm a little bit in the dark, to be honest," he told Newstalk ZB.
Nash said the fact that Sroubek had been back to the Czech Republic while also claiming his life was in danger had been a key factor in the minister effectively reversing his decision.
"If he's in great danger, you would think you would do whatever it took to ensure you never went back.
"Let's give him a one-way ticket. It costs us $110,000 to keep this bloke in jail. Let's give him an early Christmas present and just send him home."
But Nash defended Lees-Galloway, saying he would have made the right decision if he had had all the relevant information from the beginning.
Immigration NZ general manager Nicola Hogg said officials visited the estranged wife with police after a "thorough risk assessment", which was standard practice.
"On this occasion, one Immigration NZ official was accompanied by two police officers during this visit. Immigration NZ stands by this approach."
Hogg said the estranged wife declined to participate in the review at a subsequent meeting in which her lawyer was present.
"At this meeting, Immigration NZ also apologised for any distress caused by the initial visit and explained the reasons for the approach."
Mitchell told the Herald that the estranged wife had been pressured into initially writing a support letter for Sroubek, and claimed that Sroubek had threatened her to continue her support for the review.
He said given Sroubek's history of violence - he was convicted of attacking police officers and a taxi driver in the Czech Republic - and associations with Hells Angels, she now feared for her safety.
Mitchell said those fears were amplified last week when Deputy Prime Minister Winston Peters, speaking during Question Time on behalf of the Prime Minister, called her a "National Party informant".
"Now her family has even greater fears for her safety, saying Mr Peters has 'placed a fair and square target on the back ... of a vulnerable young woman already dealing with enough challenges under the circumstances'."
Peters again spoke on behalf of Ardern during Question Time yesterday, and said that National had not denied that the wife was an informant.
"That question was put to Parliament last week, and there was no answer from the National Party then, not a mutter, not a murmur."
When told that the estranged wife had been told by a former Labour Minister to contact the Opposition for help, Peters said: "So she is the informant, then."
Lees-Galloway said he has treated and continues to treat the safety of all those involved in the case very seriously.
"For that reason, I will not comment further on matters concerning these people."
