No, no, no, no!
Yes, sometimes these things get blown out of proportion, for instance until recently there was a German word for a pepper sauce that was used commonly and even printed on all the products, but some people feel insulted by it - but it has been used for decades, people have used it from their childhood on and never thought about it, it was just the normal word. If they use it now it's probably because they forget in that moment it's no longer okay or they don't even know and doesn't make them racist. Things like that, I can understand, some words just slip on your tongue. Or the insults using words that are degrading people with disabilities, that children and teenagers were throwing around when I was young, I always found it disgusting and some terms I didn't even understand, but I guess they just never thought about the actual words, they just used them because friends and older siblings used them, it was common and the meaning didn't actually matter to them.
A case like this is completely different. I don't know who he is married to and it doesn't matter. It's a word that does get used, from time to time, it's clearly pejorative and degrades athletes from certain countries because of bad stereotypes, it is not common though, nothing that would in such a situation ever slip on my tongue.
It also wasn't a joke, I wouldn't know what's funny about it anyway, it was to "motivate" Arndt, who at least taking his words afterwards, didn't feel motivated by this at all.
I'm not sure if you cannot understand it because you don't speak German, but there is absolutely no excuse for this, it makes a person racist, yes, and I'm shocked anybody would think it's somehow okay.