There is a pretty convincing argument made that a less violent foreign policy would have made the terrorist act significantly less likely to happen in the first place.
Sure, I buy that. But the guys tasked with responding to that hostage crisis couldn't go back in time and fix Russia's [domestic] policy. They had to deal with the situation they were given.
Both the military "Alpha Group" and "Vympel" were active combatants in both the first and second Chechen wars, they are branches of FSB, which were indeed responsible for the Russian presence in Chechnya since 2001.
Point being, the persons in charge of the the gas and raid in the theatre were also the guys in charge of tactics used in Chechnya.
That may be the case, but nevertheless when they were dealt with the hostage crisis, going back in time and correcting the policy decisions which precipitated it was not among their list of options.
(And were the commanders on the ground that week actually in decision making positions during the Chechen conflict? 'Following orders' doesn't excuse their participation, but it seems unlikely they personally were ever in a position to stop the conflict.)
E.g. https://en.m.wikipedia.org/wiki/War_in_Dagestan_(1999) and the following bombing of Chechnya.