You don't think this crime of racism deserves police attention?
So we have a Crime here that;
Has involved no physical contact, assault, or injury.
No property has been damaged, stolen, taken/used without consent or been abstracted unlawfully in any way.
No Money has been stolen, obtained by deception or by fraud, or like above, been unlawfully abstracted or used in any way.
Inded, it is entirely possible that the alleged victim didn't even know he was a victim until after somebody told him that he was.
I am not even sure that there is a civil case here really.
Saying that the player concerned was a useless overpaid waste of skin might well be considered slander at a stretch (Since it impugns his professional capabilities)
Waving a banana at somebody or calling them a jungle Bunny may not be very nice, but calling somebody a jerk or a ******** isnt very nice either and I do not see why one sort of obnoxious behaviour should warrant police or state intervention over all other sorts.
So I guess the answer to your question is No.
Or at least No unless the police really do not have anything more important to deal with.
(Whether or not the football club can exclude/ban him for it is a different matter. The Club is a private organisation and as far as I am concerned they can exercise their own rules any way they see fit. Indeed, I think there is way too much state interference in how private clubs can operate, but that is a different subject for a different day)