That is an unfortunate accident, and I hate to see anyone perish in an aircraft. But gosh, the accident report reads like he thought he was invincible. Really? 55 hrs total pilot flight time spread over 30 years, then jump into a squirrelly handling amateur built aircraft with a virtually untested turboprop powerplant. Really? Do we see an accident chain building here? There is much that can be done to the aircraft to tame it down and make it a fast, sporty, and safe aircraft. I doubt any of those mods had been applied. The addition of the turbine would not be among those mods recommended to improve the aircraft. I am sorry about the loss of your friend, but I don't think you can blame the aircraft design for that.
Unfortunately, many KR accidents read like this one. Pilot has virtually no experience. Scrimped pennies to build an aircraft. Many that saw it thought it was substandard. Alternate engine was used to save pennies. Pilot crashes on it's first flight. Rarely is the airframe itself at fault. Often times it's the engine, but the handling characteristics of the plane in it's stock form is a definite contributor when the stall/spin/loss of control following the engine failure or partial failure happens. The user group has done a lot to address those characteristics. Unfortunately, those modifications are not included in the plans, so joining the user group is an absolute must for anyone interested in building a KR.
-Cub Builder