Any ideas where the files for the Create 2 could be found?
The CAD you pointed out is for the Turtlebot, and includes electromechanical CAD for that assembly. I only spot-checked a few files, but the only Create-relevant CAD in that package I found was an STL of the robot's outer dimensions. The Create 2 manual should have enough information for someone to produce a solid model of similar precision, but I do not believe iRobot has released a shell for the robot, yet. Maybe you should make one and put it on a site like Thingiverse? There are other designs by iRobot that can be found there for various parts of the robot, like the bin.
Please note that I am an iRobot employee, but the postings on this site are my own and don't necessarily represent iRobot's positions, strategies, or opinions.