Perhaps things are different that what I understood.....
A-6E Intruder is the entire military designation, does this mean that the US military paid Grumman, a royalty each and every time they used the word "Intruder" in conjugation with the A-6? How about the likes of Global Security or Wikipedia? How about the Intruder Association or You Tube?
I'm sorry, but there is legal precedent for companies loosing their copywrite/trademark through common usage in the US - Aspirin is one such case, originally a trademarked name for acetylsalicylic acid, made by Bayer, now it's the generic name.