edit: Yes, I think couples who want to play BDSM games should ensure at least that the one who is "dominant" and tying the other one up etc should take responsibility which includes staying sober.
I don't want to call for a ban on BDSM (which wouldn't be very enforceable and wouldn't go down well with all the couples who do engage responsibly) but if you happen to be drunk you shouldn't be tying up someone else and covering their mouth.
And just to be clear, I'm not blaming the alcohol itself, I'm blaming him for thinking this would be a suitable activity to engage in while drunk.
although I dont think it says the victim had been drinking
It doesn't, but he was.