You’re right of course it’s racism, he knows his audience. But his schoolyard bully tactics always make fun of the unfamiliar, perhaps you mean Anglo sounding?
Because I’m pretty sure he would make fun of his own family name (Drumpf) if it belonged to an opponent. And I can’t imagine it would be any better if they were named Nieminen (Finish) or Svobodova (Czech) or Nikolakopoulos (Greek) etc. Same with first names.