Is it illegal to defend impossible statements in Germany?
"The greatest commander of all time"?
Hitler had a string of successes with brinkmanship diplomacy driving German expansion during the 1930s. If he had stopped there he would probably have been hailed as the Father of the first European Superstate. But he didn't.
Hitler then carved up Poland between Germany and Russia. If he had cheated the Russians and invaded them in defence of the Poles, he would have gained all the lebesraum he wanted, and had the unqualified support of France, the US and Britain. But he didn't.
After Guderian and von Manheim had conducted their brilliant blitzkreig through the Low Countries, Hitler could have been master of all Europe if he had extended the fight to a British invasion. And if he had kept the momentum going, he would probably have won. But he didn't.
And finally, he could have let his skilled generals have their say in the invasion of Russia. But he didn't, and instead wasted German and Russian (and lots of other Eastern European) lives like water. And comprehensively lost the war for Germany.
So it is hard to see how he was 'the greatest' . Charismatic, possibly. But, in the end, spectacularly unsuccessful....