When is it too much?

I asked a couple of questions in the post just before this one about your MLK experiences and memories. I know it was kind of random, but somethings been eating at me and I've talked to a couple of people about it and I was just wondering what you guys thought. Here's my issue - please share with me your thoughts and ideas (even if you disagree with me, I still want your input).
Last week, the girls came home excited because they would get Monday off for MICHAEL's birthday. Yep, Michael. Cory and I were baffled and asked who that was. Of course they were talking about Martin Luther King, Jr. We quickly corrected them and told them it was Martin, not Michael. They were adamant that his name was Michael - that's what their teacher and her assistant told them. This annoyed me because I have NEVER been told that Martin's name was Michael. So Cory and I talked about it and it rubbed him the wrong way too, so we had decided to write their teacher and ask that they please teach the proper history to our children and not confuse them. That night after dinner, I called Amy - my best friend- to see if maybe we just slept through 12 years of history when it came to MLK day. She confirmed that she had never been taught that either. But she hopped online to do a little research as I ranted and raved about how annoying this was. She stopped me when she discovered that Martin was actually named Michael when he was born and for some unknown reason his name was changed to Martin (after his father) at the age of 6. - So now you've been informed too (can I ask why I'm 25 and have never known this?). But that's not the only issue I have.
That same night, the girls were sharing what they learned about ole Michael (Martin) and all they kept saying was that "some people" burnt his house down because they didn't want him to speak out anymore. Nothing was said about his speech, or civil rights or anything. Just that these people wanted him to keep quiet. Now, I am left to assume that these people were the "nuts with the hoods on". This, again, bothers me. We haven't really talked about MLK day in this house because this is the first year the girls have been given a holiday for it. Maybe this is my problem. But I don't feel that our 6 year olds need to know about these "bad" people doing bad things. The whole point of celebrating and remembering this day is so that we can remember his influence on Civil Rights. I feel like teaching them this stuff is just a little too complex for Kindergarteners. I corrected the girls by telling them the real reason we remember this day and MLK was that he wanted everyone to get along and be given the same opportunities (or something to that effect).
So why does this bother me, you may be wondering... I have NO problem with the girls learning history in school, even if its a bit controversial. All I ask is that they be given the right information and on a level that they can comprehend. Please do not cloud their minds with "extra" facts that are not really relevant to the issue at hand. Especially not at the age of 6. Am I out of line here? I've never been a teacher, but am I wrong for now worrying that my children are not being taught the history that matters - but the history that their teacher finds interesting.
I haven't written a letter to the teacher yet as I am torn between letting her do her job and being "that" parent that teachers dread. I just don't see where teaching our children that "some peole" burnt down his house is more important than his influence on Civil rights. Now I'm not saying that she didn't share with them about Civil rights, but all I know is that they could only tell me about these people when I asked why we remember MLK. So obviously that was all that stuck in their minds. I guess in my mind, I feel that each year history should build on itself. Start off with the simple stuff first - His name was MARTIN and he had a DREAM. Remember that and then we will move on to something more complex next year. Am I wrong? What do you think?