According to one of my Turkish mates this incident is deeply racist. Turkish people are often called "schoonmaak Turk" in The Netherlands, which mean's a Turkish person working as a cleaner. And this is evidently based on that disparaging idiom. He's very sure that this applies to Iceland as well, because even though the Icelandic don't speak Dutch and the Turkish immigration to Iceland is quite different from that of The Netherlands, SURELY this is racist.
Conversely, Turkish fans mocking the Viking celebration the Iceland team does is fine, that's just silly primitive superstition.
Nationalism is weird.