And I would deplore to go back to high school, learn a bit of high school mathematics, specially parabola...and join us in a few years.
You can not fire a 3000 Km missile at a target 300 Kms away and hope it will reach its maximum speed at a minimum altitude.
A projectile, which accelerated to Mach 20 will cover the same amount distance , either vertically or horizontally.
A 300 km range missile will take the same amount of time to reach its target 300 Km away as 3000 Km range missile will take to reach a target 300 kms away) ..regardless of the difference in their speeds.
The difference is 3000 Km missile has to follow a lofted trajectory to cover 300Km horizontal distance, whereas 300 Km can follow a it optimum trajectory.
Those minute altitude correction nozzles on Shaheen 1A, 2 and 3 are for improving the CEP of the missile, they do not offer significant maneuverability to the RV to avoid interceptor missiles.
Plus the interceptor is getting real time updates from the Radar and has active radar homing , as to movement of the missile..and a proximity fuse to go off in the vicinity of the missile.