Structural stiffness is really difficult to deal with, it will add more movement to the piping system if your support is connected to that structure that gives high deflection. In my own opinion, the snubber may not absorbed the SAM since this is a movement from shock load and not thermal. You cannot eliminate seismic anchor movement, they are given and added to the restraint node. Think of a support location with a minimal or negligible movement with respect to pump anchor point, the large difference of displacement created by the structure movement creates forces and moments on the pump. Eliminating the siesmic anchor displacement on the structure is not connecting or isolating the support form that structure.