This is such a sad accident!
The ground rumors are a bit different to the newspaper report. It wasn't a flight instructor but a self-fly PPL with a friend taking a 'jolly' on a hot, sunny Saturday.
Apparently he flew out past the Ngong hills, turned around and tried to fly back in. Altitudes range in this area between 6500 and 8500 and the reported wind at Wilson airport that time was 32kts! It seems he was trying to fly over a ridge into a 30+ headwind on a hot day at altitude in a Reims150 with two people up. Eye witnesses say he turned around in the Rift Valley and was battling a strong orographic downdraft and hillside convective turbulence. In short he didn't make it.
Such a shame as this is the aircraft I did my PPL in and I have fond memories of its quirks, patience and long-suffering vibe. Hard to find anything else to say other than ... such a shame!!