Tasers are not really suitable in these circumstances, and are notoriously unreliable. The two wire attached fish-hooks that shoot out are easily deflected, for instance by belt buckles or armour, and both must find a purchase if the electrical charge that follows is going to have any effect. When used in Police situations, they are a "first attempt" non-lethal option to stop a suspect, with normal firearms ready and aimed by supporting officers should the Taser fail.
CS would be a dodgy option too, as the crew will become contaminated whether they inhale it or not, their masks will be limited protection as it can enter their system through eyes or any exposed moist(sweaty) skin.
A more suitable sidearm would be a revolver loaded with a high fragmentation safety rounds.
But all this assumes the attacker has breached the security door, or has coerced the crew to open it?