As many have noted, the lyrical content was no worse than what was heard from the Steppenwolf tribute act or the harmonica band that performed "Folsom Prison Blues."  Additionally, any stroll down the midway confronted fair goers with plenty of t-shirts, hats, posters and the like promoting mistreatment of women, violence, illegal drug use, profanity and more.  Meanwhile anti-abortion activists posted highly visible pictures of bloody fetuses while an entire booth was dedicated to Confederate merchandise (not something that African American or Jewish families would consider welcoming or family-friendly considering the long history of antisemitic and white supremacist groups using the Confederate Battle Flag).  

It's pretty clear that the fair needs to establish specific rules and apply them to everyone.  This year it was completely arbitrary.  The duo who were ejected are owed a full and sincere and highly public apology.  They did nothing to deserve their treatment.