Interesting audio. The last thing tower told him was that he was too low.
Sounds to me like lack of terrain awareness in VFR conditions.
The “too low” comment was in relation to the controller being able to provide “flight following” for him (radar coverage). 1000’ AGL is fairly normal for a helicopter on a local flight. I do agree with your “lack of terrain awareness in VFR conditions”, and actually it was “Special VFR” conditions at the time with the fog layer base at maybe 1300-1500 feet in the area. His last reported altitude were around 2000 feet before the crash.
mark