No. Postmaterialism is to materialism as relativity theory is to Newtonian theory. Just as relativity theory incorporates and expands Newtonian physics, postmaterialism incorporates and expands materialism. Moreover, just as relativity theory required new ways of thinking about physical reality, postmaterialism requires new ways of thinking about a greater reality consistent with empirical evidence.
Another example concerns the relationship of quantum physics to relativity theory. While both theories require basic changes in how we understand time, space, energy, and matter, quantum theory also requires a radical shift that motivates why we need to expand our notion of physicality in a postmaterialist way.