I think its cool. It's great shorthand for that topic. You should develop it, and look to partner with someone. You should also scope out if there is a definitive source for this already.
In order to build up the traffic and attention you'd need, I think you'd have to REALLY compile a large body of interesting content as well (bios, quotes, photos, posters, books).
It's a good domain, but it sounds like work for some party that is passionate about the topic, and it doesn't sound like a huge money maker though (even for break even). Might be a good way to attract attention for upsells though.
Again, extremely good shortcut... but "to what?" is the bigger question. In terms of free content, posters, etc... I would have to wonder if you'd be better off taking a slight detour and making it about the broader concept of the civil rights movement (with King as a segue).
Best of luck,
~ Dudley B.