There's nothing implicit in what's going on. It's clear that Apple leadership promised the backdoor to people in governmental power and got great monopoly power in return.
I agree with the first part of your sentence (it's 100% speculatiom on my part), but the fantasy would be thinking that Tim Cook cares about child pornography so much that he would turn 180 degrees in his principles after just 1-2 years.
The fantasy part is thinking that someone in the DOJ is offering up some sort of antitrust amnesty in exchange for reporting potential instances of CSAM to a private organization.
While this collusion theory is unlikely to be true, NCMEC is not just any "private" organization. NCMEC was established by the U.S. Congress in 1984 and has received up to $40 million of funding from the U.S. Congress every year.
