Actually, this “trick” is a space-time continuum issue. Setting the date for 1 Jan 1970 is pre-Apple founding. So doing so is impossible, as your iPhone would exist in a time before the company Apple was founded, making it a paradox, hence the iPhone is bricked.
This whole thing reminds me of telling a room full of 11yo kids, “Don’t look out that window at those elephants or they’ll stampede and hurt somebody!”
...where’s that Picard_Double_Face_Palm gif when I really need it???