Without going into a long diatribe about what causes a gas cylinder to fail or what even counts as one in poor condition it is still not my view that the ejection of the seats and occupants was anything to do with a gas explosion.
Cylinders fail rarely and for a relatively limited number of circumstances. Crystallisation of the metal caused by over heating and over pressurisation during many filling cycles is one cause. This generally causes a rupture which will cause the cylinder to move but not create the explosive energy to throw two seats and the occupants out.
A cylinder with heavy internal corrosion will provide a source of ignition and fuel for an explosion but this would occur during filling due to adiabatic heating completing all sides of the fire triangle.
A cylinder will not explode due to impact damage. If it was attached the airframe and received enough damage to split then it could force a stream of directional gas out but not enough to rip a seat and it's occupant out let alone two in different directions. A loose cylinder recieving enough damage to burst would become a projectile. Again probably doing serious damage to anything it hit but not enough to eject 2 seats and occupants.
Why do you think ejector seats use rockets and not compressed gas.........