As far as I'm concerned, Kurn had the right to ask Worf and Worf had the right to fulfill his brother's wishes. The Klingons would "consider the matter closed."
My only problem was Worf's extreme shortsightedness. Between Picard giving him a dressing down after he killed Duras and the raid by Riker and security when he was burning some incense in his quarters on the Enterprise, I would have thought that Worf, the elder brother of the House of Mogh, strategic operations officer of the second most important sector of the alpha quadrant, and commander of the Defiant, would have stopped for a minute, sat down with Kurn over some Rokeg blood pie and bottles of prune juice and blood wine, and planned some leave time to maybe hash out this whole Mok'tovah thing away from Deep Space Nine out of uniform, off-duty, and out of sight.
Sisko wouldn't have had a problem with this at all .. he let Jadzia off the hook for keeping Kurzon's blood oath of vengeance and neither Kurzon nor Jadzia were even Klingon. But she didn't do it on the Starfleet administered, Bajoran space station she was posted to.
But dude --- in your quarters? On Deep Space Nine? And asking the Ferrengi bartender for the incense for the ceremony?
Worf was asking to get caught. Hmm...maybe that's what he wanted because he really didn't want to kill Kurn.
As far as the memory wipe, I consider that murder, and I will go out on a limb and say that Kurn and other Klingons would consider it a dishonor. Kurn wasn't killed in glorious battle or ritual suicide. He was robbed of his honorable death by erasing everything he was, or worse, keeping him prisoner in the shell of Rodek. Worf didn't even give him the death howl. Gowron got a more honorable death -- hell, Duras did (no death howl there, though .. fine with me).
Worf was both un-Starfleet and un-Klingon all around.
Edit to add: And to add insult to injury, fracking Bashir goes along with it!!!! I guess anyone can just take a visit to the infirmary, ask Bashir to erase their brother's memory and, for a small fee, it's done. Rom could have had Quark's bar years ago!