Really nice explanation from someone who knows a thing or two about images/photos (Dr. Neal Krawetz is the creator of https://fotoforensics.com and specializes in computer forensics).
He wrongly interpreted CSAM scanning. He said that Apple will scan your photos and if finds something, it will send photo to Apple. Which is absolutely not how it works. Photo is only scanned before uploading to iCloud Photos. Apple already confirmed it to iMore and it’s clearly stated in Apple papers from press-release.
You're very clearly missing the forest for the trees. Right before uploading to icloud, "Apple will scan your photos and if finds something, it will send photo to Apple."
This process is automated and turned on on most iPhones. Most iPhones will have automatic photo upload to icloud enabled, and that's when this scanning takes place.
> Most iPhones will have automatic photo upload to icloud enabled,
I highly doubt that with how each photo is 10+MB and Apple only gives an abysmal 5GB of free iCloud storage, which includes everything else. My iphone 6s backups got to 4.5gb on their own years ago, turning off photo storage was the only way to avoid paying for iCloud storage outright.