As one person said earlier, David Conn is an investigative journalist and it's his job to tackle thorny issues. Having read that article I can't see it being anti-City in any noticeable way.
David Conn has quite correctly pointed out that no one really knows who owned Tevez. There was an international arrest warrant issued for Kia Joorabchian two years ago re his alleged involvement in money laundering and I doubt there are many on here who know who FATF are? FATF are a "inter-governmental body whose purpose is the development and promotion of national and international policies to combat money laundering and terrorist financing". Recently there is much concern amongst government bodies/ agencies etc that there could be a high level of money laundering etc going on in football...in fact, there was a white paper/ report issued about money laundering in football earlier this year.
So in short, Conn has highlighted the lingering doubts about the true ultimate ownership of Tevez, the Kia Joorabchian connection and the ongoing concerns of money laundering in football. All of which is true. I very much doubt the Guardian's lawyers would have let Conn's article be published if there were any issues.
In short, what is there to worry about...City have purchased the player, they own the full rights to him, everything has been signed off by the Premiership & FA etc etc.