Does a shunt regulator protect other ICs from high current transient spikes?
The shunt regulator being isolated from the VIN node via a resistor is not going to help you with spikes, surges and sags in the VIN rail. It is a proposed misapplication of such a part. 

Instead you want to look at two things. For over voltage spikes you want to use clamping devices such as tranzorbs to turn on somewhere above your operating voltage and absorb the extra energy in the spikes and surges. For voltage sagging you want to apply capacitors as temporary energy storage on the VIN when the load demands extra energy for short periods of time.

You can also use inductors and/or ferrite beads to isolate noisy circuits from ones that need to be quiet in conjunction with the above techniques.