Given the technology of the era, how else where people supposed to gain access to it? And so what if they made a profit doing it, so long as other companies or individuals had the right to distribute it also. In the end more copies would have been distributed and listened to.
And as for the "MLK-Hitler poster" argument, that would be fair use and wouldn't be stopped by copyright.
IANAL, but as appalling as I think they would be, MLK-Hitler posters are practically the textbook case of fair use:
1) Transformative factor: To say that an MLK-Hitler poster "adds new expression or meaning" to the original is to make the understatement of the year. I may not like the new aesthetics, but they are certainly there. Furthermore, the posters are powerful imagery (value is added) to those who hate MLK.
2) Amount: The posters only excerpt a single frame of a much longer video.
3) Nature of original: The video is not abstract art... it documents a historically- and culturally-significant event. This gives poster-makers broad latitude to do as they please.
4) Effect on market for original: Any argument that an MLK-Hitler poster is a substitute for video of the original speech is a non-starter and doesn't pass the giggle test. You would have to argue second-order effects, (that the posters ruin MLK's image, and therefore reduce demand for all things MLK) and courts haven't really gone for that (if they did, you couldn't publish an unfavorable movie review that showed a still from the movie). If anything, it probably inspires people to try to find the original and pay the (outrageous) licensing fees.
So an MLK-Hitler poster passes the fair-use test on every single count.
Are you serious? I'm fairly sure you're protected by the first amendment for selling MLK-Hitler posters. In fact, you can Google for those items now. Here's one:
Their existence only proves they haven't been sued yet. But, you have a good point. Perhaps I am mixing Trademark, and Right of Publicity, with Copyright. All of them apply in this case, and have been used in the past to prevent the unauthorized use of MLK's image and works.
As a public figure, MLK ('s estate) has greatly reduced right of publicity, so I'm not sure how you think that would come into this. You are allowed to criticize celebrities. Even in California, MLK's personality rights wouldn't survive his death anyway.
As for Trademark... what is the trademark here, and how would anyone be confused by an MLK-Hitler poster? I don't think anyone is going to buy an MLK-Hitler poster thinking that they are getting MLK-brand doughnuts (or even MLK-Hitler brand doughnuts).
And as for the "MLK-Hitler poster" argument, that would be fair use and wouldn't be stopped by copyright.