I'm not big on his music, but if Tyler the Creator, a man who raps about drug use, rape, murder, suicide and mental health issues (also a presumed brony) can be on the Regular Show, I think a man who sings about essentially being happy can be on FiM. I've yet to hear a song too offensive by Andrew WK and not once heard a curse word in any of his material. I think the closest is "We wanna have fun and we wanna get wasted" in "We Want Fun". Really, I see no issue in this.