Hitler only came to power in the spring of 1933 and spent most of the year consolidating his power. Some measures constricting Jewish rights were passed, but the coup de grace, the Nuremberg Laws were not passed until 1935. In 1933 there were no deportations, no camps and no mass murders. This guy was a time traveler?
I think people in some Jewish communities knew about Hilter before he came to power. Sure, the average U.S. person might not be familiar with Hitler in 1933, but let's not forget, there were Jewish people from Germany in the U.S.
Hitler hadn't made his feeling about Jews a secret before he came to power. I don't find it hard to believe Jews would greet Hitler coming to power with extreme antipathy. I don't know if there was a concrete plot, but it doesn't surprise me that they would be trash talking him.