The media and others were trying to paint Zimmerman, not a s your ordinary southern white racist, but as a racist southern Jew....not just white, but an EVIL JEW !!
When that tanked, they were left to grab on to whatever they could.
In fact it is not necessarily a Jewish name (it just means "carpenter" in German and that occupation was hardly monopolized by Jews).
Ethel Merman's real name was Zimmerman and she was not Jewish. Arthur Zimmermann, of the infamous Zimmermann Telegram in 1917, does not appear to have been Jewish. I had a classman in high school named Zimmerman who was a Catholic.