I would lean to an angled approach from downwind that hit heavy sink.
How close to the terrain would you need to be to get a sink rate exceeding the rate of climb of a Baron at MTOW at 9500ft, with ~ 20kt winds aloft?
Quite close I would think. A few hundred feet; possibly a lot lower.
I don't do any "mountain flying" but have flown straight over the top of the Alps and the Pyrenees a number of times.
However I don't believe winds could have done this. The aircraft hit the ground with a massive vertical speed. Looking at the pictures, at least two seats were ejected out of the cockpit, several yards out, ripping off the roof in the process, all despite a near-zero horizontal speed. One to the right and behind, one to the left and over the LH engine. Both ejected with occupants still strapped in (visible in the first picture). Horrid.