Not all bosniaks are muslim. Yes they're predominantly Muslim or Sufi ( which isn't actually traditional Islam). But there are orthodox bosniaks as well as ones whove adopted other religions through intermarriage. It's really not difficult to understand.
That last name is common in Germany, mainly Serbia, but also in many other countries like Albania. Last names don't mean shit because people marry out of their religions all the time. How stupid do you have to be, in this day and age, to think you can accurately determine someone's religion based on their last name?
It literally says in the article: To see him standing there, one might never guess he suffered more than 10 skull fractures and was almost killed by two men who attacked him, yelling, "f--king Arabs!"