Your answer is purely speculative and doesn't rest on any solid historical evidence as far as I can see. The ultimate source is Guggenheimer & Guggenheimer's Jewish Family Names and Their Origins wich is the most comprehensive and reliable Jewish onomastics dictionary. In it, you'll find that Katznelson, along with Katzeneleson, Kazenelson, Kaznelson, is derived from Katzenellenbogen (also Katzenlenbogen, Katznelbogen). This comes from the placename Katzenelnbogen, a small principality in central Germany whose major source of revenue was protection money paid by the Jews. There is additional information on this in The Oxford Names Companion which was cited in the original answer which there was no reason to question in the first place.