No, the original poster was right - I truly don't think City have grasped what Social Media does... and whilst your right about City posting would spark keyboard idiots - that's because City have allowed this to happen by being 'reactive' instead of 'proactive'.
Clubs like United and Liverpool... and many more (businesses, movie companies etc.) all employ influencers – people with blue checks that reach large audiences that will post positive articles about them and negative articles about their rivals/competition, and because they have a blue tick, and reach a larger audience research shows people will more readily believe and agree with what they post.
Now Football is a bit different in so much as some influencers are fans first and will do the clubs bidding for free - people like Luckhurst or Mitten, who United fanzine writers that have bizarrely got themselves into a position whereby they can influence by being 'journalists' – if Joe Bloggs posts something on Twitter, not many take notice - but if Joe Bloggs, Chief Sportswriter for the MEN posts, a lot of people suddenly take notice.
Then you have journalists that maybe have no real affiliation with a club like United, but because the club have played the game right and got such a massive audience online, they will tow the clubs line for fear of missing out on that audience – clicks generate money, simple as that.
You then get a more sinister side – that we're very familiar with whereby it's political due to our owners nationality – blue-checkmarks posting derogatory things about them... which again, Joe Public will believe verbatim, without realising those said Posters have very strong ties to political/national openants to them... How many of the nobs we regularly see posting sh!t on Twitter have Qatari links for example.
What City need to do is - instead of taking on the crap that's already there - is to start 'influencing' positivity about City... it won't be easy, but they have to start getting blue checkmarks to bang the City drum... as some have said, look at how Rashford's campaign has been reported opposed to Vinnie's campaign for the homeless... that's down to United using their influencers to constantly post positive stuff.