City are playing the 'taking the higher ground' game and have been for years.
Banning him from the away end during the week was cited as a safety move, rather than a character/opinion based one.
They were damn right too, and I think people don't fully appreciate it. He could have felt empowered in a loud away end after a few pretend beers to make provicative gestures, affect songs etc. Whether in shit banter or malice, doesnt really matter, in a potentially charged atmosphere. Which could have pissed off City fans and before you know it the dortmund fans think they have an issue with them and it escalates between two groups for no real reason.
It was a good call by the club and I don't think they were even trying to send any messages or show any teeth, I think it was a purely black and white safety assessment.
Fwiw while I am saying I thought it was the right move, I am not saying I agree with their general 'higher ground' approach btw.