Given that DS9 showrunner and co-creator Michael Piller was in fact Jewish, I highly doubt that the Ferengi are some sort of stealth Nazi propaganda. They're either a mockery of the "happy merchant" stereotype beloved of anti-Semites, or (more likely) just a critique of greed and capitalism itself.

What's funny is that Leonard Nimoy (Jewish) based his portrayal of Spock on the idea that the Vulcans were the space Jews. This idea kind of comes to a head in the 2009 movie, in which a guy named after a Roman emperor destroys Vulcan, causing a Vulcan diaspora...