His last sentence is the best clue we have.
Guesswork here, but Ozil is very vocal on Muslim causes. He wouldn't be best pleased at how the sub-human communists in China behave, for example. So Maybe that's where the falling out lies? Ozil wanted to speak, the club said no because - money. Must be something like this or he wouldn't have added the final sentence.
Ironic, seeing as the club and all the players have been vigorously promoting racism and terrorism for the last few months.