Judge Taylor refuses to close the courtroom and says, "People generally see what they look for, and hear what they listen for, and they have the right to subject their children to it..." What does he mean?

Bob Ewell has already set a precedent for the type of information to be conveyed in this trial, "I seen that black ni**** yonder ruttin' on my Mayella!" Judge Taylor knows that people will see what they want to see and that they must hear everyone's testimony: not just Bob Ewell's.