"...party co-leader Alexander Gauland was cheered for saying, apparently with approval, “that Germans don’t want to live next to a black football player.”
As much as people would like to deny it, the man is probably simply stating a fact. The author is ascribing nuance to this statement that is opinion, not fact.
"One local party official, Björn Höcke, called Berlin's Holocaust Memorial a “monument to shame”..."
Well, yes it was an entirely shameful event in German history. A certain amount of shame helps maintain a cohesive society. In some ways this is simply another statement of fact.
"another, Jens Maier, called for an end to Germany's “cult of guilt” over wartime genocide and warned that Merkel's immigration policies would result in “racial impurity.”"
Eventually Germany will have to end its guilt over the war. Keep the shame, end the guilt. The racial impurity statement is again, fact. You can like it or not.
So, what is the problem?
The problem is that we already had to eradicate these people one time.