United's true fan base is probably around 100th (at tops) of the ludicrous 659m number claimed - therefore the claim about revenues / click bait for positive stories about them doesn't make sense to me. Negative stories about city will generate a lot more hits than positive ones - but negative stories about united could be the biggest earners of them all due to the number of football fans that hate them.
Protecting market share would be harder with constant media negativity, or positivity towards rivals, especially when united are so dire on the pitch - therefore it's not beyond the realms of possibility that the likes of the trinity mirror group get regular presents via the Cayman Islands to bring their stories in-line.