I think this is totally unfair, and misrepresenting the entire situation of that hostage crisis. Someone reading this might think the Russian authorities just slaughtered civilians haphazardly.
You are referring to the Moscow theater hostage crisis. And for those who don’t know about it, Chechen terrorists, including suicide bombers held those (I believe 850 or so) in the theater hostage. Any attempt by the Russian authorities to storm the building and save the hostages would have meant the suicide bombers would detonate their bombs, killing all of the hostages. The Russian plan to end the standoff was to pump a chemical into the ventilation system to subdue the terrorists, the chemical ended up killing nearly all of the terrorists, and unfortunately 130 civilians died as well (but many more lived of the 850 I believe). The use of this tactic was criticized, but honestly, what wiggle room was there?
I can’t imagine many more complicated moral dilemmas than this. Try to storm the building conventionally. and you risk everyone dying, give in to their demands and who knows if they keep their word. I really don’t see how people can say this is a clear black mark on Putin’s record. I think drone strikes, which kill civilians and are chalked up as collateral damage have more room for moral criticism than the method used to take down these terrorists.