Ms Wilkinson was unable to comment on individual cases, but a spokesman said it was not uncommon for her to intervene in "special circumstances".
O'Brien, who lives in London, has been back to New Zealand regularly since the 1960s and wants to eventually retire to Katikati, north of Tauranga, where he has a 2-1/2-acre property.
Born in Britain O'Brien came to New Zealand as a 10-year-old in 1952 and lived in Tauranga and Hamilton until he returned to London in 1964.
His siblings Robin Smith and Gillian Page live in Tauranga and his parents lived there until they died about four years ago.
His son came to New Zealand on a student visa and was applying for residency.
In 2004, a statue of his
Rocky Horror
character, the butler Riff Raff, was erected in Hamilton on the site of the barber shop where he worked before leaving for Britain.
-NZPA