It's not that the fans are shocking, there just aren't enough of them.
That's about the size of it. Man City were a reasonably sized club, but they were the much smaller of the two top flight clubs from their city. A bit like how the BS are compared to us here in Liverpool. Abu Dhabi may have bought their name and location, and they can even buy up all the unsold tickets to make the attendance figures look respectable, but they cannot purchase a fanbase that wasn't already there. They can expand the ground all they like, too, but again, the fanbase isn't there. The order of things in Manchester is already long established. They aren't pinching many 'fans' off United, and few people outside their city give a crap about Abu Dhabi FC. All they may attract is a portion of those transient 'fans' who never actually go to the game but bleat on about supporting whoever happens to be winning at the time via social media. Even then, those glory hunters surely are aware that Abu Dhabi's 'success' will forever be tainted by cheating and viewed as meaningless by the wider sporting community. It's not like there is much kudos in jumping on the Abu Dhabi bandwagon.
In a small way, I actually feel a bit sorry for their players, because no matter what the assembled team go on to do, they will never be respected like the true greats of the game are/were because the whole thing is corrupt and built on cheating. The whole project is the Lance Armstrong of English football. It's tainted and smells very dodgy.