Np, we've become COWARDS in dealing with aberration and perversion. We had no problem in 1985 that a perfectly healthy young lad llike Marty, with a beautiful girlfriend like Jennifer (Claudia Wells in the first movie, Elisabeth Shue in the second and third) worried that making a play for the girl destined to be his mother, even under a false pretense, might scar him enough to render him a homosexual. Of course, that was utter nonsense, although Marty correctly makes the connection between psychosis and homosexualiry...he just gets the underlying cause wrong.

Doc, at least the 1955 version oh him, not comprehending the change in slang nor the openness in which society discussed sexual matters, simply didn't get what Marty said. Comical, and should be left alone. However, probably the scene was deleted because it didn't help with the flow of the film.