Some info - gumbyk got it right, single pilot ops "IS" approved for the S-76B, what is not currently known is what avionics was in the aircraft and whether IFR operation was authorized. The S-76D is certificated for single pilot IFR operations.
Bryant didn't own the helicopter, it was owned by Island Express Holdings. Island Express is a 135 helicopter operation that does flights to Catalina Island and charters. Bryant may have been leasing this aircraft and it may have been operating under Part 135. If that was the case, authorized IFR operations would be indicated in the operator's FAA approved operation specifications, providing the aircraft was authorized for single pilot operations.
The NTSB will do their job - personally I believe this pilot (although instrument rated) got into IMC and was attempting to turn around and head back, possibly to KVNY.
That's my thinking at the moment as well, with what has been described, but I'm half a world away...
I suspect that this wouldn't have happened if they were operating IFR unfortunately.