That story is not supported by a single quote or piece of evidence. I don't believe that City would ever consider suing the PL over a proposal to ensure sponsorhips are "fair market value." All our sponsorships have already been independently checked repeatedly as part of UEFA's FFP regulations. UEFA didn't even accuse us of this (their allegation was not about the scale of sponsorships but where the money may have come from.) The CAS decison re-inforced the fact that our sponsorships were fair value.
This is just another bogus Daily Mail smear story from an unnamed source which is designed to damage City (and Newcastle). It could only have come from someone who is the loop ie a senior Chairman from one of the other PL clubs. If I was a betting man and, given that the story was created by Matt Hughes, my money would be on another toxic briefing to the Daily Mail from Daniel Levy.