The most likely model for Alex Brady is
Steven Spielberg, whose early TV work includes directing
Murder by the Book (1971) (1971). Spielberg had already been spoofed in
Mind Over Mayhem (1974) (1974) as Steve Spelberg, the boy genius played by
Lee Montgomery.
Another possibility is that he was based upon
John Landis who was responsible for the 1982 deaths of Vic Morrow and the two children during filming of
Twilight Zone: The Movie (1983). Spielberg was the executive producer of that movie and was also considered responsible for their deaths.