I am wondering if it was a combination of the two. For example, I know of a case that was a combo of 'random opportunity' and ' organization.' There was awho was a part of a sex trafficking ring. he happened upon a girl who was crying on a park bench. So he offered her a hot meal and then nabbed her and took her to the 'bus' full of young sex workers that he was driving to the next state.
It might have been something like that for little William. Some perp with contacts in a pedo ring that happened upon him and took the opportunity to grab him and go?
Yes, I think it's plausible. The perp was associated in some way with the pedo ring that clearly exists in that area. Happens to see WT running around with no adults around - boom. So it's both opportunity and a pre-existing motive and a network of people who could hide him while they work out what to do. Gross and very disturbing but a lot more possible than other alternatives, imo.
(3 years 3 months... it's now Feb... so he's 3 years 8 months? Kids get a lot less pudgy in the face as they grow. Looking for a kid that looks just the same but with different hair probably isn't enough. People need to be taking into account increased height and probably a slimmer looking build)