Mike;
I would see no reason that a laminated pen that mimics the color and pattern of a service ribbon would be inappropriate, or offensive to anyone. As a 5th generation veteran I am pretty sure that nobody would raise an eyebrow. After all, we make pens in the image of the flag, and that's a lot more particular in how it is handled and represented.
Now, the actual mechanics of making the blank may be a little more problematic. Some ribbons are more complicated than others, and the thread count for the thickness of the stripes is pretty precise, but it should be doable. Seems that I may have even seen one somewhere at one time. Can't remember, I've drank since then though.
If you give it a try, post the results