It's one more salvo in the continuing campaign of political scientists who engage with the broader public to convince us (with pesky evidence) that almost nothing that we think matters in politics really matters, or matters much, or matters in the way we think it does. Here's the core of Bernstein's 'untransformational Reagan' argument:
Take a look at the Reagan myth. Did Reagan “ideologically shift the nation in his direction?” If we’re talking about voters, the answer is pretty clearly no. As Northeastern political scientist Bill Mayer showed in The Changing American Mind, if anything, public opinion on many issues became more liberal, not more conservative, during Reagan’s presidency (see also a nice post from George Washington University political scientist John Sides).