I agree (again) with teachertraveler. Accidents happen, sometimes it's not our fault but others is.
Let's wait for the investigations to finish and clarify everything. Media is releasing info but in a messy way, confusing everybody.

If like they said in the first place, this guy was with his friend and all were having "fiesta", I'm pretty sure they all drank a lot (one of the attractions for young people when coming to Spain). He was not allowed to enter the disco because he was in a bad condition (really drunk or something else?), right? Then, if he had so many good friends that are now mourning their loss, why none of them said "hey, don't worry, i'll take you home because you're not ok to go on your own"?.

I would never let a friend going home alone if I saw he or she is not "feeling" ok. I would make sure he/she grabs a cab!!