Basically what the article is saying is that you should have two devices. One device is your "normal" phone. Basically it has no privacy and lets you blend in to the crowd. The other device is your private device that you keep unlinked to your identity.

I think this concept is called the "Gray Man" in the prepping community. If you try to go fully private or full prepper, you stand out. You want to appear normal so that would-be adversaries don't have any more reason to target you over some other random person.

EDIT: Whoops, commented on the wrong article. Here's the article in question: https://insanelyfree.xyz/blog/ditch-your-privacy-phone/