I don't get this stance that the club should be "held accountable for believing a lie", at the end of the day everyone can get lied to if there is nothing to disprove what someone is telling you(was he pictured in London at all?), so it's not really some "great embarrassment"(maybe to the ITKs who take their reputations too seriously) that they gave the benefit of the doubt based on what they were told.
There has to be a liar in this story if Jorginho ends up at Chelsea, could it not be that the press release made by City was a case of saying here's what we are being told in response to that Chelsea rumour so someone is lying, if that turns out to be an ITK, his agent, ADL it's their reputation which will take the knock and leave people sceptical of them for future reference. They have set the pieces in play to tarnish someone's reputation for either spreading false rumours or lying in negotiations and messing us around(includes confirming the deal is still sound in response to press reports). This is a business where professionalism counts and a loss of integrity will be held against them in future negotiations, we'll see who really comes out of it worse if these so called professionals conduct themselves that way.