As I understand Russian roulette you spin the cylinder between pulls rendering each pull the exact same 1 in 6 chance
In that scenario, the would be correct.
I think Terry Kath picked up a semi-auto, thinking it wasn’t loaded.
I believe they were drinking, and since they were musicians, especially it being the 1970’s (when this happened) I suspect other “things” were in play as well.
Reportedly, the other band members said he had a surprised look on his face. I’ll bet. He was my favorite guitarist at the time, too.