I think this massively underestimates how self important and pompous they are at UEFA, and I think it is almost certainly what did not happen.
Mark Halsey recently confirmed what we all suspected, namely that he was told what to say in a match report because the decision had been made higher up the food chain that they wanted to take action about a particular issue. That was in relation to PGMOL but I think you have to be naive to think that does not go on at UEFA level as well.
The booing was not a new thing in November last year when the possibility of charging us arose. It had been done on a number of occasions previously, and had been commented on at some length in the media. Booing the UEFA anthem however is a disciplinary offence - that is why they wanted to charge us in the first place. (The self important nature of UEFA in this respect can be seen from the fact that UEFA's regulations prohibit the crowd from booing the opposition's national anthem at an international match - which you can understand - OR the booing of UEFA's anthem. So these jumped up little knobheads place their little piece of corporate branding on the same level and as deserving of respect as God Save the Queen, Deutschland Uber Alles, La Marseillaise and all the other national anthems that have inspired billions in times of war and peace.)
The idea that every single UEFA official observing a City match since the booing began missed this clear disciplinary offence, but then one guy decided to mention it where no others had seems to me to beggar belief. The reality seems to me that UEFA decided that their dignity was being offended and the guilty party would be charged. Whether they previously ignored it in the match reports and this time decided to take action, or whether they wanted to act and (a la Mark Halsey) told the official what to put in his report seems to me to be as broad as it is long. They had decided enough was enough. Equally, I cannot remember an occasion on which UEFA has opened a disciplinary investigation and then not followed it through with a charge. (Or the FA for that matter). But this time, following a series of extremely adverse articles in the media, they wisely decided not to follow through with this particularly petty and vindictive action.
The idea that some suit at UEFA went off on a frolic of his own and was then put back in his box by UEFA seems to me to be incredible - as in, incapable of being believed. They wanted to charge us, but they bottled it when they saw the shitstorm they had kicked up.