pumping sleeping gas into the theater and killing the hostages was a pretty aggressive approach
I was rather critical of that plan as well, but some others pointed out some things to me.
1. The main problem was that the Russian .mil would not tell medical/EMS on scene what was used. (Gaseous Fentanyl) and had they known, they could have pushed Narcan or equivalent and saved 90% or more of the hostages.
2. I can't remember if Beslan was before or afterward, but the Chechen's are not for show. They'd have killed as many if not more/all of the hostages. They knew what they were doing and were interspersed with the hostages with machine guns and explosives at the ready.
If they'd simply told the first responders what the gas was, it would have been a HUGE win for them. Stereotypically Russian of them. They're very decisive in terms of taking strong action, but are utterly paralyzed with CYA and bureaucratic authoritarianism the rest of the time.