Fortunately, the epithet only appeared in the flash build, and not the general build that would have been released to the games 5M paid users, according to Minecraft's current producer Jens Bergensten.
According to the developer, the epithet had been left by a disgruntled user who had been banned. Bergenstein had Minecraft player, "Sorry about that =( I thought I had banned that user."to a
Hopefully, Mojang will be more thorough with checking what gets through in its crowd-sourced development cycle, which is one of the hazards of allowing relatively unknown users help work on your project.