Sure, it's not nice at all to have these things but had Koulibaly not got sent off for a) fouling Politano for a deserved yellow card and b) reacting to the ref as he felt he was being wrongfully penalized, no one would really bother that much aside from the people who witnessed it. Had it been Maksimovic or Albiol, no one would claim it was "a response to racism". It's a silly argument. Why then and not 50 minutes ago when it was louder? Those monkey chants were loud in the first half and almost non-existent in the 2nd half. He heard them again only after he started complaining & clapping to the ref, so saying it was because of that is simply him playing the victim card. Reminds me of Messina's Zoro who heard general jeers for tackling everyone like crazy all night long, getting away with it - he even almost cut Martins' legs in half after he "reacted to the racist chants" but luckily he was a split second too slow - and when he started complaining that he didn't commit foul and there were loud jeers and taunts and a few minutes later he simply left the pitch and everyone was like "racism" again, when in fact all that happened was that he got pissed at losing 0-2 at home at that point and was at partial faul in both goals. Zoro pretty much was an awful player who was always playing too hard, fouling people a lot and not being a very good ball stopper (but leg stopper) and fans hated him. So it was no surprise that our fans had a banner calling him 'Infame' that was paid in bananas and peanuts. Which was worse than the "chants" that he allegedly heard at the Messina-Inter game. Of course if someone is and behaves like an asshole you shouldn't emulate him and become a worst version, but let's not put the blame on one side only.
With Koulibaly it was really bad because he gave no reason to be abused like that other than wearing a Napoli shirt and the fans were rather emotional because of the rivalry and the heated atmosphere between these clashes. You won't listen to that shit when we play vs Genoa, Empoli, Sassuolo, Parma etc.
Sure, it's something bad, it's not nice to hear at all, but it's not like people are doing this anywhere else. It's an easy way to get under someone's skin (pun, damn) and fans tend to do that kind of shit no matter what. It's just that when it's a black athlete it's more likely he'll hear that kind of gesture, while others will hear something different. I don't think anyone called the Ronaldo carnival whistles "racist" when he returned to Italy and played for Milan. It was pretty much the same. And Ronaldo had a sentimental attachment to the club, manned up, scored a great goal against us and took it to the fans. Zlatan also was hearing all sort of shit when he played for Milan.
There's no correlation with Koulibaly's sending off and the racist chants. Two completely different situations in the same game. One was a bad decision by the player, the other was a terrible collective action of a large group of fans.
Now whether the club wants to ban these people, sure, it's fine. But this is Italy, it's not England or the USA or Australia. Others will do the same in the future. You can't ban a few people and make this stop, this was already the process 20 years ago, yet it persists. Whether we like it or not, it's a cultural thing. That's a way for some people (not just in Italy, but more of a regional thing) to irritate people. I mean they'd probably bang a bunch of chopsticks together if there were many Chinese players in Italy and they wanted to get under their skin and do "Indian" sounds if some native Americans were around... It's just that the method against the black players is and sounds the worst of them all and it's rather frequent in Italy compared to other civilized European countries.
P.S: Whether we like it or not, our fanbase consists of many Italians belonging on the far right of the political spectrum.