No one takes four different benzos at once unless they've got a specific outcome in mind.
You can no more predict a heavy recreational benzo users's night than you can predict what someone will do blacked out on ambien or alcohol.
It totally impairs judgment, and people who are addicted can quickly escalate without realizing it.
This very well could have been an accidental suicide.
In any event we're all speculating. But I seriously doubt anything about this was accidental, even if the benzos were recreational. The drugs didn't kill him. The hanging did.