That's correct, disregard SIP in that case.I thought SIP was only relevant if you are creating Catalina usb using Catalina OS (I am on Yosemite)
Have you tried using the 'createinstallmedia' command that Apple offers ?I thought SIP was only relevant if you are creating Catalina usb using Catalina OS (I am on Yosemite)
sudo /Applications/Install\ macOS\ Catalina/Contents/Resources/createinstallmedia --volume /Volumes/USB --nointeraction