What if they did? It was developed in the 1920s as a pesticide. The chemoical is still produced for the purpose in the Czech Republic under the name “Uragan D2” (Czech “uragan:”, like German “zyklon”, is “cyclone” in English).
The fact that it was used as a tool for murder— even with the producers’ knowledge— does not render the present companies culpable in the Holocaust.
That’s like holding Exxon-Mobil to blame for arsons and murders using gasoline.
/johnny