I have been through this before, if there are two reps in a geography and one refuses the larger territory, they will approach the other rep and make the offer to them. That's why CC asked for a quick decision in his email.
Read the Last paragraph before next steps in his email:
If you are placed in the new organization you will be encouraged to accept or decline the placement as soon as possible. In order to facilitate your decision making please consider that new regions and territories are likely to be geographically larger........