Mr Sowman said nobody wanted to be reminded of the former resident.
"I've got no issue with what they're trying to achieve, but to link us back to the Beast of Blenheim I guess is inappropriate - we're actually trying to move on from that part of our history."
He was concerned about victims in the area who were trying to get on with their lives.
"To keep seeing the place referred to with those connections is disappointing for them."
Air NZ has since changed Blenheim's name to Ghostheim on the grabaseat site.
Mr Sowman said he was pleased about that but an apology to residents would be appropriate.
"They might care to do that or they might care to give us a few days of cheap seats to make up for it."
Air NZ did not reply to questions about whether it would apologise to Blenheim residents.
Wanganui District Council Mayor Annette Main said she thought Air NZ's promotion had missed the mark.
"I know you've got to have a sense of humour, but something needs to be funny I guess or relevant.
"I think they were running out of imagination, certainly on the Blenheim one and certainly on the Wanagnui one (Wronganui) as well."