Marxists invented the concept of socialism, so it’s a bold claim he would claim they corrupted it. Marxists would say the same thing about Hitler’s appropriation of the term.
Overall, the German economic system is not what meaningfully changed under Hitler. It remained a sort of mixed economy. What made the Nazis odious was Hitler’s consolidation of dictatorship powers. His cancellation of elections. The Nazi Party’s banishment of certain groups from government and civic life, and eventually throwing those same people into concentration and extermination camps. The concept of a “master race.” And then, of course, invading the entirety of Europe and attempting to impose his will everywhere.
If Hitler had just said some things in favor of socialism and moved money around, no one would have cared much. Every world leader was doing that — it was the intellectual current of the day. It was all the other stuff, the virulent racism, the genocide, the conquest, that set Hitler apart and makes Nazism uniquely evil.