In theory, I would support every possible policy that could possibly exist in real life to be available in the game. Including and especially policies like these, primarily on the grounds that I do not see a way in which racial segregation could be a benefit to a world leader, and it may dissuade any (potential) Nazis who play from actually pursuing demands for segregation in real life by making them want to look further into the policy to understand why the game makes it a negative.
That would require an incredible amount of economic and social understanding to be imbedded with the values and impacts of segregation policies, which is a burden I think is too high for Cliffski, morally not in terms of intellect. For this, I would leave it to be done by anonymous and experimental modders, but then they have the same burden of getting the values right.
As with segregation itself. The problem with segregation is a complex one. To take the example of one of the biggest states to be criticised for it, Rhodesia, it was implemented not even as a racist policy but as one to limit the influence of the settlers. If you think about it, you had natives who were not educated or culturally involved with the economic laws and practises of the colonising British settlers, nor access to the same wealth, and ultimately this would have led to total purchase (annexation) of the native lands, resulting in a situation where 100%, not 50%, of the land belonged to whites and 0% to black natives. As a result, they passed that law, with the assumption that education would be introduced and improve the lot of the other, native, 50% until eventually segregation could be abolished as there would be no chance of the black population being exploited. This ultimately did not happen, the European 50% thrived while the native African 50% stagnated and were dominated with tribes and eventually this boiled over into the history we know today of Rhodesia (now being Zimbabwe, a sign of who ended up winning that conflict).
The reason I give a detailed history of segregation, being that it was never, in history, intended to purposefully repress, but rather to prevent instability and economic exploitation. It was a purely American experience and then a Nazi German experience for racial segregation to be done as we believe it to be done today. Do we need to create two separate kinds of segregation? Do we need to create tiers within a Segregation Policy that makes it so that once reaching a level of education it stops being enforced? There are so many complexities and strange theories tied into the concept of segregation that it would become a nightmare system to try and simulate.
That being said, political imprisonment is something that is not nearly as convoluted and is much more evidenced in the modern day, and I would definitely support some policies that allow for imprisonment of specific groups, at a very high democracy, corruption, etc impact. It would never really be viable unless you were doing a brutal-dictator run, but I think it should be an option anyway.