Not to beat this into the ground, but on further reflection you are correct in your insinuation that 17 year old Mel Brooks was too much of a pussy to take on Hitler via sarcasm while Der Fuehrer was alive. So rather than bravely mock him while alive, Mel Brooks joined the U.S. Army Engineers and sought to actually kill Hitler (or rather help others kill him - by defusing land mines). Once the Schicklgruber was dead, Mel could safely write The Producers.
Brooks' contemporaries agreed that he was a pussy, but brilliant.
It didn’t take any courage to mock Hitler in the 1960s. Moe Howard and Charles Chaplin openly mocked Hitler wile he was in power.
It’s in this context that I make my observation.
Mel’s mockery doesn’t compare to the other entertainers’ mockery in terms of possibly paying a consequence.