/Why rake it up now?/
Those claiming to be victims have been trying to pursue this for a long time -- it's only now that the British Government is accepting their case.
As to your other points -- it was before my time, so I cannot possibly understand what was going on. Thing is, though, that British records from the time basically confirm the fact that the British in Kenya did commit what they are accused of, including "...beatings, solitary confinement, starvation, castration, whipping, burning, rape, sodomy, and forceful insertion of objects into orifices...". Officials at the time apparently knew about this but did nothing to stop it.
Even though some or perhaps most of the Mau Mau rebels were violent in kind, you can't possibly justify some of the above actions at all -- in any way. "They started it", "meet fire with fire", etc. -- all of these arguments are morally repugnant. Indeed, it makes
my blood boil to think that we should forget what happened and to accuse the survivors of such crimes as play-acting or similar.
Furthermore, most of the claimants have never been accused or convicted of being Mau Mau rebels themselves -- and could just as easily be innocent bystanders.
Sources:
http://www.thetimes.co.uk/tto/opinion/columnists/benmacintyre/article2981528.ece
http://www.thetimes.co.uk/tto/news/uk/article2983138.ece
http://www.bbc.co.uk/news/uk-17734735
http://www.guardian.co.uk/commentisfree/2011/apr/11/mau-mau-empire-british-government-responsibility