I think this rule could actually be good.

Imagine the black eye the rabid US politicians would get IF it turns out
that Airbus aircraft have greater US contents than the newer Boeing jets
?

"This Boeing plane was 42% built in the USA"
"This Airbus plane was 43% built in the USA.


Even if Boeing still has greater "made in USA" contents percentage, it
would outline the fact that Boeing is now relying on foreign content and
subsidies to a verty large extent and this would hurt egos in the USA.