There is no one today that is undeserving of "punishment for his sins". God still needs lots of tools for His plans for us. He still wants us to spread the gospel to everyone, so for our purposes and perspective, everyone needs to be saved. God works on a higher level though.
Of course we all deserve punishment for our sins, but Pharoah’s sins were especially heinous. Similarly, I think it’s possible that God hardened the heart of Hitler when he decided to invade Yugoslavia to punish a popular revolt against his puppet government - instead of going directly to Russia - the very difference in timing that caused the Nazis to be trapped in the Russian winter that led to their demise. God let Hitler’s psychosis become a weapon against himself, much as Pharoah’s hardened heart with regard to the Hebrews.
We also have to keep in mind that God foresaw the choices that both Pharoah and Hitler would make with their free will, thus, the hardening of their hearts would not be an encouragement to sin, but a re-directing of their foreseen sin to an outcome that would become their just punishment, instead.