Sounds like the idiots are those who would license and schedule a play about Al Jolson ... and then be shocked, shocked, to find there's something about blackface in it. WTF?
I like to give audiences credit until proven wrong. They probably would have had the LEAST problem with it, assuming most of them know at least that much about Al Jolson, and that the issue is presented well (DR Druxy gets the benefit of the doubt here!), and especially with the use of the disclaimer.