I wouldn't give any power at all to Hitler. I wouldn't name him head of state. I wouldn't even let him vote in a town hall meeting about fixing a water main leak. By the principles you have stated, then, I shouldn't let anyone be head of state, and I shouldn't let anyone vote to fix water main leaks?
So what you say is that if someone is clearly ethically wrong, it doesn't matter whether it is legal or not.
That is also my opinion. If we are lucky, we are born into a society in which what we perceive to be right aligns with what the rules say. The next step down on the luck ladder would be a society where there is misalignment in some cases, but there are mechanisms you couls use to change the rules (as is the case in most free countries), and then there are cases where not only are the rules unfair, but you have no way of changing them. In that case resistance is only way to deal with it.
Now with the wisdom of hindsight you can say, the Nazis were clearly bad. But this was much harder to see for thr people during the time. I know because one of my grandfathers was in the Wehrmacht while the other hated the Nazis. Money quote (translated from German): "Everybody thought Hitler would make Germany great again".
