Why is it your hypothetical worst case scenario can become true but not my hypothetical worst case scenario? You're the one worried about the CSAM "code" being on your device regardless of iCloud Photos being off, so you should also be worried that backup code being on your device regardless of "iCloud backups" being off. Double standards it seems.
What's "b.s." is you believing that Apple would actually search willy nilly whatever they want with this tech. I don't believe that, therefore I'm fine with CSAM on device detection AND iCloud backups code being on my device. So, to answer your question, no that's not what I'm saying, but that's what you're essentially saying.