The article is being disingenuous about data not being deleted unless it's overwritten with 1's and 0's. Technically that's true, but:

Most data being deleted is equivalent to a piece of paper being placed in a trashcan, and it's "permanently" deleted when that trash gets hauled away to a landfill (or supposedly recycling but that's another topic). Technically it's still forensically accessible, but it isn't accessible by any normal means. That piece of paper may not have been incinerated, but for the majority of practical purposes, it's gone.

Apple never hauled the trash away, even though they claimed they did. There should be no way for them to accidentally restore those photos, just like there's no way for you to accidentally get a piece of paper back in your trash bin after it's been sent to a landfill.

Focusing on the 1s and 0s skips past the fact they failed to complete the first, obvious, essential step. If they didn't delete it the simple way, they would never have gotten to the 1s and 0s step. This isn't just a simple oversight, and those pictures were still very easily accessible, just not to the people who should have been in control of them.