My opinion only.
Everything I've read and seen about this case tells me that it would be out of character for Jason to take off. Especially with little to no money and no personal belongings on him. In an interview, his mother said he was very, very responsible. He was also shy. Striking out on his own would force him to step outside of his comfort zone. I get people can be spontaneous and do things out of the blue, and can act contrary to what is normal behavior for them and their personality. And I think there are a few missing person cases where the MP acts impulsively and does things unlike them, but not in Jason's case, at least, not to this degree. He had a lot going for him if he stayed put, including pursuing a career he enjoyed, and a loving, supportive family. It didn't appear he was oppressed or stifled by his parents in any way and would want to leave. By all accounts, he really had no reason to start a new life.
Definitely don't think this was some sort of snatch and grab job, where a van pulled up, the doors opened, and thugs got out and dragged him inside, and then drove off.
I think this was a crime of opportunity, a combination of random chance and coincidence. I think it was committed by a casual acquaintance, someone unknown to his family and community circle, but known well enough by Jason where he felt comfortable interacting with them and didn't feel threatened by them. I believe this because his mother said that anyone and everyone, and she emphasized and was emphatic about everyone, who ever knew Jason, was interviewed and cleared. This leads me to believe it was someone his family may not have been aware of, but Jason knew. Someone who, by random chance, just happened to be driving by (or maybe pulling out of their driveway) while he was walking to the school and offered him a ride, and, pressed for time, he accepted. If there were a moment where he might act out of character and be impulsive, I believe this would be the more likely scenario than taking off. He had someone waiting for him and it would save him from a sweaty, brisk walk, a decision spurred by his sense of responsibility.
To give you an example of what I mean, when I was about 13, I was out for a walk one rainy day, and a former friend’s father just happened to be driving by. He recognized me, did a U-turn, and offered me a ride. I declined, my house was around the corner and I didn’t need one. Had he been a bad person (just to be clear, he wasn’t, he was a very nice man), and had I gotten in the car with him, never to be seen again, my family would’ve had no clue who he was, and chances are, he’d never have been interviewed. And unless there were witnesses to me getting in the car, he’d never have been found out and taken the secret to the grave with him when he died unexpectedly 2 or 3 years later. Something similar to this is what I think may have happened to Jason. Again, this is my opinion as to what happened, subject to change as things evolve.