The problem is real, but this solution seems to not really solve it in any practical sense.
So, 90% of photojournalism outside of the major cities, then.
That's not a thing. Straight from Apple:
"When a photo is taken in the new Reference mode, the camera captures signed sensor data that Private Cloud Compute develops into an unalterable reference image. Reference images can be viewed in the Photos app alongside the main image"
So this only helps prove anything if you can share the original, unedited image. You can share it alongside an edited one, but you must also be comfortable sharing the unedited original if you want to prove you own an iPhone 18 Pro. Er, I mean prove it's "authentic"
Now I think C2PA had allowances for what you're talking about, but that also ended up resulting in it being easier to break.