The part I highlighted from the previous post didn't show very well. Christie didn't announce it. Media who shouldn't have access to the portal info, announced it.
The reason Christie entered, even though he's likely to go to the draft and likely to return to the U, if he comes back to college, is because he needs leverage with DTA and the U. If he wasn't in the portal and withdrew from the draft he'd be locked into the U. They could then low-ball his NIL and say "too bad, we used your offer on other players in the mean time, guess you're out of options." With the portal open for him, he keeps maximum options. So in the unlikely event he returns to college, he'll have a landing spot, probably at the U, with NIL money. If the money's gone, he can assess other options.