I am not here to debate whether there is some ethical or moral dilemma on the line, but rather if there is a statute on the books which establishes such an activity to be a crime. I don't believe that to be the case. Show me and I will stand corrected.
I think it all boils down to this.
Fender has taken some legal measures to protect their financial interests. If what someone does with a fake decal has no effect on Fender's income, why should Fender care and/or persue legal action.
Fender is not out one thin dime if someone sticks a fake Fender decal on a used instrument and sells it. Fender has lost nothing, and that's why they don't waste their time and money going after $0 loss.
Otoh, if someone is making fake Fender products and labeling them as real Fender parts, Fender stands to lose income and will likely prosecute to protect their interests.
90+% of the criticism of people who put fake decals on their own stuff with no intent of resale is just a bunch of people wanting to bash/judge someone else. The how's and why's of the bashing and judging are endless, and Fender couldn't care less because they aren't financially affected.