Also, with all we know about the NSA, I'll be very surprised if the U.S. government didn't already knew and if they did, didn't try to take advantage of it.
I.e. an order (with due legal process) by USA government to not disclose that vulnerability to any Chinese companies would be possible and binding, but not the other way around. That's what being a USA company means, no matter where your sales are.
If Intel explicitly does some kind of US exceptionalism explicitly, the EU, China and other governments will probably require to be aware of the vulnerabilities no later than other governments.
How could the EU possibly let Intel sell CPUs, and let Intel inform other governments of vulnerabilities first? So that the other governments have a time window to play with the vulnerability against the EU?
In that case, sure, but I was talking about a voluntary disclosure, which is the case here.