I have not seen a rationale for it. I hypothesize that it's simply that they thought they would stick with the municipal boundary. As I said, in this case this was a very odd municipal boundary. Innisfil has been through a series of very traumatic municipal amalgamation fights with Barrie—in 1967, 1982, and 2013. Several of them resulted in court fights.
If you look at the submission from the Town of Innisfil itself, it was done by the mayor. It's almost an agonizing submission in itself, which expresses concern about Innisfil losing touch with the rest of Simcoe County and other rural areas, and that being put together with Barrie is difficult. But then they say they recognize the needs of the population, but whatever you do, please put the name “Innisfil” in the Barrie riding. It reflects that traumatized position. But I think when you put together the whole history of it, the character of how people have lived their lives, regardless of where those constantly moving municipal boundaries have been, the people in this area are oriented to the south. I think that line there to the Fourth Line of Innisfil roughly reflects the change, or, if you will, the watershed, in people's behaviour.