"I just heard that (about Kopua) and actually I'm not sure about that," she told Radio Sport.
"Casey is an amazing player and if she wants to do that it's up to her.
"From a New Zealand netball point of view it's a little bit bad...you need to build players that are coming through. To bring back players, as good as Casey is, I don't know if that is the right move.
"You need to work with what you've got, can't keep going back and asking people. Casey and I are older. Coming into an environment...she might have been a great leader when she was in our team...there's (now) an age difference.
"It's a tricky one. Straight off the bat, it doesn't sit well and not something we should potentially be doing.
"No disrespect to Casey, she is an amazing player, but from a growth point of view and trying to move forward, going backward isn't the right way."
Harrison said her retirement decision was final this time after she had quit netball on a previous occasion to play beach volleyball.
"I'm known to say never say never but I'm calling time...a tough decision but I always wanted to be in control of it," she said.
"I wanted to leave when I was feeling good."
The Northern Mystics' progress was taking time to consistently appear on the court.
"I just wish you could see the flair and skill consistently — once they get that nailed everything will come together and it will be amazing to watch," she said.