I agree that it's not the most likely scenario but it would work better than some of the abduction attempts I've been reading about.
As for Aunt TB's "stranger danger" instruction... maybe.
There's plenty of evidence that kids who have received extensive "stranger danger" training are incredibly easy to fool. There's also evidence that many victims (not just children) freeze up and become compliant as soon as they are accosted.
I don't know of any way to predict in advance who will react by taking action and who will freeze up. If there were some way to figure it out, I am absolutely certain the military would love to find out about it. Estimates are that only about 10% of soldiers on the field of battle shoot to kill. The vast majority do not want to kill another human being even though their own lives are in danger.
And that's after a lot more training than Aunt TB could possibly have given the girls.
For a real life example, here's the cctv tape of Carly Brucia, 11 years old, being abducted:
Carlie Brucia Abduction - YouTube
Carly's family was certain that their child knew to fight, knew not to go anywhere with a stranger, etc. But as you can see on the tape, she definitely didn't look happy but she went right along with Joseph P Smith when he grabbed her arm and led her away.
That is by far not the only example I've read of but it's the one with the clearest videotape of the encounter.
IIRC, shortly after Carly's abduction, Oprah did a show wherein she showed a group of parents hidden video of their children being led away from a busy playground by a "stranger".
The "stranger" obviously was part of the experiment, and the parents were all adamant that they had taught their children to NEVER go with strangers.
The looks of absolute horror on the faces of those parents, GOOD parents, as they watch their children fall for the old puppy trick, or cast on the arm, etc., has stuck with me all these years.
I try to never assume my child will do "the right thing" if presented with a potentially dangerous scenario, but I certainly do not fault parents who truly thought that they had thoroughly instilled in their children the "stranger danger" method.
As a side note, I hope that children will also now be taught that it's okay to speak up and tell when the "bad person" is someone they love and trust. Again, it may be less than 100% successful, but as parents we have to at least let our kids know that we will listen to them and NOT blame them and that it doesn't matter if it is a teacher, or a relative, or a friend's parent, etc.
IMHO, the danger of being hurt by someone known to them is greater than "stranger danger", so it certainly is worthy of a family discussion.
Back OnT: I think the girls were taken by someone they knew or who had (rather easily) gained their trust (ie boat ride, sodas). I do not think the family has done anything to the girls. I am BAFFLED by the FBIs seemingly assuring message that they girls are alive. It is not very FBI-ish, IMHO. I hope they are right.
Hold your babies close today, and give them a few extra kisses.
Oh, I'm gonna be giggling all day, despite myself, about Gamerpinger, binger, dinger, winger. Lol. Not making fun of the guy, just loling about the name game we have going on here!