https://cimg9.ibsrv.net/gimg/pprune....292c0f6192.jpg
Final Report to come in 60 Days after review is completed .
CFIT , TAWS turned off , Deteriorating Weather .

Re TWAS , The text says inhibited , not turned off , could have been U/S . whether this occurred before departure would be interesting to know. Normally in VFR it is not a MEL item since in VFR you are supposed to remain VMC and fly visual.clear of terrain . Deteriorating weather is a factor but not the cause, as, in VFR if you cannot maintain VMC you have to turn around ( easier said than done in the mountains, hence the issue. )
Reading that list I think points 5, 6 and 7 are closer to the actual cause.

ATC Watcher,

a small but important detail: You can fly VFR in less than VMC (and hence IMC) in most countries in certain types of airspace (Golf; Delta - with clearance). Its the grey area that gets you through the grey when flying low and still able to see sufficiently (usually 1sm, but varies a little according to aircraft and country).

No, you can fly VFR under lower reduced visibility /ceiling condiions (e.g. VFR special) and even lower ones in helicopter , but never in IMC conditions. My point here is that separation with terrain in VFR is always visual, not using instruments ,and this whether you are in normal or reduced VMC . And we not talking about inadvertently becoming IMC in VFR, a different discussion.

What is less than VMC minima? IMC. Reduced visibility/ceiling is IMC.

Have not read the report but it would not surprise me to find out that the TAWS was intentionally turned off to prevent nuisance warnings in a mountainous airport. We used to do that in a previous job as it was distracting. At some airports, it is a requirement to get close to terrain for takeoff and landing. We already know that there is terrain close to us.

Of course, you better know what you are doing, regardless of the availability of TAWS.