In general I agree with this. (Without respect to this particular crash.)
If GPS signal is sufficiently degraded or lost, TAWS is probably unavailable (highly dependent on what navigation system is on board). TAWS might have saved them. But needing TAWS implies loss of situational awareness.
This flight crashed in the mountains ~6 miles north of the ILS 24 approach course. At ~12 miles out on the approach course, the ILS course width is ~1 mile. A full needle deflection translates to 1/2 mile off the course. A flight is not established on the approach course with a full needle deflection. Course intercept with localizer or VOR is basic instrument work - GPS not required.
The flight requested ILS 24, later they indicated airport in sight, requested and received a clearance for a visual approach. That means pilots have full responsibility for terrain and obstruction clearance. The visual approach requirement is to maintain contact with with airport.
It seems to me they went off course, by a lot, for reasons I'm not clear on, and then descended prematurely into hostile terrain at night, which is likely why they lost visual contact with the airport. The terrain blocked their view and by the time they realized they were descending into hostile terrain they crashed.
If that's what happened, GPS signal loss is perhaps an instigating source of distraction and confusion but I do not see how it's a primary factor. If the signal becomes degraded, navigation should indicate it (auditory and visual) and that source is ignored entirely. Falling back to ground based navigation should be familiar, it doesn't need to be as precise as GPS, the instrument approach procedure has terrain clearance baked into it.
Best practice is to follow the instrument approach procedure to the final approach fix, then do the visual approach - especially at night which many have argued constitutes instrument flight conditions - mountains will be invisible. Pitch black on black.