The only scenario that seems to fit the circumstances here is not a stranger abduction or a random RSO.Imo, the scenario that fits the situation is if someone that Dylan recognized or was acquainted with, came by the home that morning. Maybe the realtor from the House For Sale, from across the street. Or a neighbor that knew his dad, and stopped by to check in and say hello. If dad worked out of town for long periods, he probably had someone nearby who checked on his property occasionally, or something like that.
But for Dylan to have everything in his backpack with him, I think he thought he was getting a ride to his friends in B-town. And if he was suddenly offered the opportunity for a quick ride, then I can justify his not calling anyone yet. Maybe he planned to do so on the way.
So I hope that LE has looked closely at all of the neighbors and friends of dads already. Even the kindly old neighbor and the local realtor and the friend who helps him stack the firewood.