Gonna say the Chinese used it to test their satellite retrieval and repositioning technology.
In the 1970s? They barely had television.
It didn't shift to the current orbit in the 70s. From the wording of the article it seems like they expected it to be in a location based off earlier data.
However, it is way off that target today. Seems to me something else changed the orbit not gravity as they thought it would.
There doesn't seem to be a lot of things that cause those types of adjustments.
I remember reading something about the Chinese having a vehicle or something that can change orbits and capture there satellites etc... What better way to test those things than on a defunct and seemingly forgotten satellite?
I'm just speculating, I'm no rocket man.
No, but according to the article it was probably commanded to fire thrusters to take it out of it's orbit in the 1970s, and it slowly drifted to where it is now.
Almost certainly, it was commanded to fire its thrusters in the mid-1970s to take it westwards. The question is who that was and with what authority and purpose?