China is one of Iran’s best allies and oil buyer. Notably they agree on one thing, they hate the petro-dollar. Iran will sell oil in anything but the US dollar (preferably gold) and China is happy to buy it all on those terms.
Who Iran be involved in a plot to hijack a plane when 2/3rds of the passengers are Chinese?
No way.
...not unless they really think the Madhi’s return is eminent. (ie: the twelfth imam is coming out of the cave)
The Madhi will only return with the scent of the blood of millions ... Iran’s Twelver leadership has long said they will encourage that return sooner than later.