The deletion almost certainly was because of the username, not the content of the answer. There was a user's flag pointing out that while the answer in and of itself might be ok, the username certainly is not.
As the comment by Dave pointed out (he did not put up the flag, btw), this was a rather gross violation of the be nice policy, so the deletion was justified by this, not the content.
Edit: As @virmaior pointed out in comments, we can change the username. As this was the main concern, I undeleted the answer and deleted comments merely referring to the username after setting the username to the system default.