The law says “seal”, not emblem. There is a difference. What laws are there regarding logos or emblems?
The USC code is about the official seal. People wear those FIB hats all the time and no one cares I would imagine if one made a CDC hat no one would care as well. Same for coffee mugs. Making a silly hat is one thing forging a government document is quiet the other. If you bought a blank blue passport from China and added a picture and typed in information would one think the government would not crack down on it? Why would anyone think that buying a fake.document and filling it out would be any different. Forged is forged