Bill's view is close to mine. In my work with other companies, this has often popped up. You have to be really careful about this stuff.
I know in the mainstream gaming industry people have made copies of Hecklar & Koch products by not calling them so and implementing them in the game. This has been done many times with other firearms companies as well. Certain companies get antsy about it, like Colt, while others really could care less.
It is a case by case basis. While Cessna itself may not have a problem with it, Textron, the parent company is the people that hired the guy to check on copyright infringements on behalf of them. So while the guys at Cessna are comfortable with the idea, they unfortunately and ultimately have no say in it. That is the square hole that Textron keeps trying to get us to put a circle through.