Okay. I assure you the meme is very popular today and used widely on forums and websites that are anti-Semitic in nature or preach of some global Jewish conspiracy.
Edit: Many young Trump supporters, that buy into crazy conspiracy theories, thought the ushering in of a Trump Presidency is a blow to this Jewish cabal that seems to run the world. This is why asked about the nature of his Avatar, to which OP replied just as I expected.
If you browse /pol right now you'll probably see it posted at least twice on the front page at any given time.
Have you really not seen the Happy Merchant meme used widely on the internet?
Usually the likes of people who believe in the global Jewish conspiracy, also think 9/11 was an inside job...or PizzaGate is real.
The bottom line is you saw his avatar and thought Jew. That is anti-semetic.