Rocky Horror Picture Show vs your 6yo daughter

It is totally up to your own individual Parenting preference , but is a late night showing with audience participation of the Rocky Horror Picture Show an appropriate setting for a child of 6 years old? With all of the orgy and sexual conversations I personally don't think so. Or am I just being a prude? 
  And shouldn't the vendors running such showings enforce the age restriction ratings? 
  I usually judge not what other parents do, but I felt very uncomfortable for the child I witnessed at a Halloween viewing of this cult classic. There were no other children in a theatre of about 50 adults. The child also expressed her want to leave the movie and her mother just told her to close her eyes. 
What are your thoughts on minors in adult rated theatre showing in general? I see this too often.