I saw the video in the link the OP posted, I didn't see anything in there that was controversial, the written article I feel made it sounds more hyped up.
Typically every contract with Boeing will have a clause in it saying "Boeing will furnish to Buyer, as soon as practicable, flight test data obtained on an aircraft of the type purchased hereunder, certified as correct by Boeing, to evidence compliance with any performance guarantees set forth in this Agreement. Any Performance Guarantee will be deemed to be met if reasonable engineering interpretations and calculations based on such flight test data establish that the Aircraft would, if actually flown, comply with such guarantee."
TC is saying the aircraft has been flying for some time now, and they haven't got updates, this is unusual. Airlines will typically also have staff embedded in the manufacturers production facility keeping an eye on frames being built, often manufacturers use these staff to informally pass on good news back to the airline. It sounds like this is not being done either.
Performance guarantees include things like flight performance, takeoff performance, landing performance, "green" empty weight, CG, sound levels, configuration (like the number of doors or slides, maximum number of passengers), results from cold and hot weather testing, and the method these guarantees are determined to have been met. Typically when airlines go to pickup aircraft they will provide the crew with a tour and experience on the latest engineering simulators, these crews typically have flying members of management and it provides another opportunity to pass on the good news and an informal sales pitch.
Everyone on here knows Boeing has been very quiet on the 77X performance, compare the detail they provide for this program in public to the 787 or 737Max, we are after the original EIS and they have yet to state basic information like maximum payload, or a range payload curve.
I saying I like to use in situations like this is the absence of evidence, is not evidence of absence. That being said, there would have been a contractual requirement for Boeing to pass on the test flight data to the customer as it became available, and the customer is saying a year since the aircraft started flying they are not seeing the data.
What is particularly bizarre is the engine performance is specifically mentioned, unlike the aircraft, the GE9X is already certified, the TCDS has been issued. The engine data is available.
The simplest way Boeing could appease EK would be to hand over that data.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949