First off, the PL would have to prove it was a sham. It didn't have to be Mancini personally delivering the consultancy so even if they had evidence he never spoke to anyone at Al Jazira, that's not in itself proof. It could have been David Platt, Lombardo or anyone else who was suitably qualified, even if they had no connection with City.
Second, great play was made of the supposed fact that we paid him more via Al Jazira (£1.75m pa) than via City (£1.45m). But this was a misleading comparison as his City contract was heavily incentivised, so by winning the FA Cup and getting top 4, he received far more than that base £1.45m
Finally, if the PL allege it was fraudulent and designed to hide expenses from the accounts, we'd simply point to the scale of our losses at that time (which totalled around £350m in the years that Mancini was manager) and ask why we'd want to hide less than £6m. If it was the difference between profit and loss, or passing or failing FFP, then there might be a case but the amounts involved are completely immaterial compared to the level of losses we were reporting.
It's a complete red herring and the PL bringing it into the charges seems to reinforce the view that they're throwing any little thing at us, however irrelevant it is. It's the optics of the charges that are more damaging than the actuality.
We can probably take comfort from the fact that if they thought they had us bang to rights on the potentially far more serious and material sponsorship issues, they wouldn't need to bother with the Mancini stuff.
My guess is that there was some tax advantage for Mancini in this arrangement and that many foreign managers in England have some sort of similar arrangement. There was certainly no advantage to us.