Earlier quoted context omitted.
This still seems like a very low bar. If the country has ANY trade treaty with someone else that has trade advantage, than it would appear like that fits the letter of the law.
We have most favored nation status with most other countries, so they generally don't have any other nation that is getting better terms than we do. That's the point of the WTO.
However, MFN status is full of exceptions. For many countries, the US could plausibly argue that they are being discriminated against despite having MFN status due to one of the exceptions to it