Well yeah, but hypocrisy isn't a criminal offence.
There's absolutely nothing wrong with the banner. The BBC are reporting it like the figure in the picture is just a stereotypical Arab figure (therefore racist), rather than quite clearly a picture of the crown Prince, who is the chair of PIF. There's not a single thing on the banner that's not a legitimate criticism of him, and it's also a completely fair criticism of the laughable nature of the Premier League's fit and proper person test. Getting the police involved is nothing more than Newcastle fans getting pissy because their club is getting criticised and trying to use the law to silence that criticism.