Detonation will still leave a large part of the rocket motor and control fins intact which can then fly uncontrolled with residual fuel burn
9M38M1 have rocket fuel for 20 seconds of flight so when this missile can hit Boeing it already dont have any energy except inertia.
Don't forget, this is a SAM system capable of high-g manoeuvres (typically 30 - 50g) of monocoque construction and so of very high strength.
9M38M1 have limitation on full rocket (on start) 19g. After use all fuel rocket decrease her limitation to 13g.
Given the initial kinetic energy of the missile at detonation (typical velocity 800 - 1000 m/s at altitude), large parts of the missile will travel some considerable distance in semi-ballistic trajectory away from the detonation point.
But missile dont plane and cannot glide. Her aerodynamics is very unstable so only a few seconds flight after detonation possible (with yaw or pitch in any random direction during expllosion) and dont have a way for compensate increasing distortion of flight.