Every study would be better if it were meta-analysis of longitudinal studies. But those cost a lot, and scientists make do with the resources at hand. But I think this study has value in its own right. I doubt this study was the only one looking at these sentiments during that time period; this is just the one that got posted today.
I think you can lay out your perspective as too narrow when trying to evaluate opinions and behavior and I believe this study has fallen victim to it, at least partially.
Racism played and still plays a huge part but the resentment against Jews was primarily caused because the Nazis convinced people successfully that they are the victims of a Jewish conspiracy around the world. The typical mechanism of populism. Of course this manipulation only works if a basic resentment already exists, which was true for Jews since time immemorial.
And this resentment did not vanish over night. I would argue that little of it remains today however. At least against Jews in Germany. There are of course very vocal exception. And it is a crowds that is indeed very dependent on outside confirmation.
