telecom engineer here (not on a Huawei/ZTE payroll). the reason why the original piece is extremely unlikely is the cost of keeping a conspiracy involving this many entities and requiring collaboration between them under wraps. you do not need hardware implants or even sw based backdoors when the system is fragile enough to get the same undocumented functionality without.

it is not needed because the quality of Huawei/ZTE and all the Chinese based tech vendors is so shockingly bad that no such backdoors are needed to achieve their objectives. shitty quality gives much better plausible deniability than a well designed backdoor in thoroughly tested code.

The big and only story IMO is that Huawei steals shit from other companies. I had my own work for control-plane on eNodeB stolen by colleagues in our Chinese site that then moved to Huawei. The company should be sanctioned all around the world and their CFO hopefully will rot in a US prison.