The other stuff is certainly possible.
But those 3 gaba'ergics together in high doses would certainly cause said bodybuilder to simply stop breathing in his sleep.
Bro, let me tell you something, I am a big guy, can drink a case a beer in one evening and 2-3 perks (5mg, regular tecs) fucken kill me, I have zero tolerance for them, anyway I know a guy who takes 12 80's a day, an 80 is 80mg of oxy's and he takes 10-12 per day. Here I am dying over 10-15 mg and this guy is taking in 1000mg per day, unfucken real, the body is fucken a crazy machine and can handle enormous amounts if it has time to build up.