Relating to Relativism

Today, Saturday, is the day that I have my conversation class. For three academic hours, which is two hours and fifteen minutes of real time, I lead a group of around 10-15 adults in discussion in English. In some ways, this is a very nice deal for me. There are never any tests to grade or papers to correct, and I don't have to worry too much about introducing complicated grammatical structures. On the other hand, my students range in age from about 15 to 45 and in ability level from intermediate to advanced. Also, this is a fairly long time to talk, so the topics must be very interesting, which generally means controversial. Thankfully we have a little library of books like A-Z Conversation Topics which prove to be very helpful.
Today the topic was "Decisions." The worksheet basically presented situations in which a difficult decision must be made, and we discussed these. As per our training, I would have the students first discuss in pairs or small groups, following which we would have a general class discussion. Some of the questions were mostly just for fun, as in "Would you rather be extremely ugly but very intelligent or unbelievably beautiful and particularly stupid?" Others, however, were more serious, like "Do you believe that men like Hitler were evil or were they simply acting according to their own morality?" and "You are 45 and pregnant and the doctor says there is a %50 chance your baby will have Downs Syndrome, what do you do?"
It quickly became apparent to me that I was no longer in America and certainly no longer in the Bible Belt. I expected that many of the students would have positions I disagreed with, but I was unprepared for the degree of difference. When faced with the question of whether they would prefer to be a cruel tyrant or one of his slaves who was kind and just, all but one chose the king. Partly, I think this is due to the fact that Russians are more straightforward and don't tend to give the politically correct answer to look good, but they all said that is better to have power than to be ruled. One used The Prince to justify her position. They honestly look at Machiavellian morals with approval. Now, I do agree with cultural relativism to a point. While I think that murder is always wrong, I think that while revenge killing is murder for us it could be justice in a different time and place. But to say that Hitler wasn't evil because he was doing what he believed in is simply insane to me. To be fair, half the class did say he was evil, but the idea that the other half found his actions in any way acceptable astonishes me. I didn't really know how to respond.
Later in the class, I had to walk away from one group after hearing one girl make the statement that people with Down's Syndrome aren't really people. I didn't call her out on it, but I made it clear in my subsequent remarks that I knew and cared about a number of people with Down's. I just didn't want her to make such a statement again since I wasn't sure how angry my voice would sound in direct response. I then found out, upon asking, that the usual course of action in Russia when a mother gives birth to a child with Down's is to send the child to a special hospital. There the child is largely ignored until it dies around age 15. That explains why I've only seen one person with a mental disability in all the time I've been here. Thankfully, the majority of the class did speak up and say this is a horrible thing.
I don't really know what to do. As a teacher of English, it is not my place to give sermons. I don't want to give my opinion in such a way that students feel pressured to adopt it to gain favor. But really, how can I be silent?