That is a concern that has been raised by one of the people who have shown a lot of interest in the model from Fair Vote Canada. That person has been wanting to learn more about the model and is trying to figure it out and has raised that as a potential concern.
I would say that the same problem currently exists in the first-past-the-post system where you can have a very large riding but you only have one person from one place. The fact that you have twice as large a riding but you have two representatives, you've got more of a chance to have people covered if you have two people from a similar area.
In order to win votes, a smart party in the nomination process would probably consider where it wants to put its candidates to draw the most votes. That is a potential chance, but I wouldn't say that would be a default or common occurrence. I'd like to give the model a chance and see how it runs for a couple of elections, and then make a judgment.