It depends. Any historical figure, good or bad, operated within a framework that dictated what they could or couldn't do. From our point of view, FDR should have declared war on Nazi Germany on 1939 or attacked Japan in 1940 ... perhaps even made far more obvious preparations for war in 1941; from their point of view, it was politically impossible to do anything of the sort. And that's in a decent state. If the SI is in Hitler's body and he decides not to launch the war, or carry out mass slaughter and genocide, or anything else along those lines, there's a good chance he'll be killed by his own subordinates.
If it was done well, it might teach a lot about real history. But it would have to be done very well.