"Well that's not quite accurate. The reality is we have a great idea, it comes with complications, we need to do a lot of analysis ... and we're all still working through it."
Tew was quick to point out that NZ Rugby and SANZAAR haven't agreed to the concept either, but praised World Rugby for trying something different.
"We haven't said yes or no to anything. We've just said good on World Rugby for coming up with something a bit different. Good on them for bringing a bid to the table that provides us with a reference point. And we're going to work it through.
"To say the south have said yes and we're on to it is a complete exaggeration. There's still a lot of water to run under this bridge."
Tew didn't, however, share the same views that Melville had about the prospect of relegation. The NZR boss said relegation is a fear for any team but is needed if there is to be fair mobility between nations in world rugby.
"I don't think anyone are going to suggest that you are not at some point in time going to have a poor season and might be at the bottom of a competition," Tew said. "If that's a year that relegation is on the table then yeah you would fear that. But obviously you work very hard to mitigate it.
"The reality is if teams don't go down, no other teams can go up and you'll have everybody in place forever. And that's clearly not something that we all want."
All Blacks captain Kieran Read, who returns for the Crusaders against the Hurricanes this week, also added his voice to the issue and expressed the need to do what's best for the world game.
"I think you can understand where they (England) are coming from around certain things but it's got to be good for the world game. So it's important we get to that point."