Well, I don't know much about Maryland law, but here's my quick and dirty take on what you were told --
This touch vs. not touch thing is really weird and not consistent with any legal doctrine I'm aware of. I could see it, maybe, if the issue was assault or risk -- like if she attacked them or seemed to be a threat to herself or someone else -- but responding to a handshake is neither. I suspect they did the whole handcuffs thing after shaking her hand because they wanted to surprise her, not for some legal reason.
Second of all, you can't take a handcuffed person on a commercial airplane. And one would think she would have said something to airport staff along the way. So I don't know what's up with that.
Yes, if you confine someone against their will (in a room, in a car/plane, with handcuffs, whatever) it is a) false imprisonment, which is a tort (civil wrong) and b) some variation of kidnapping (what, exactly, depends on the state criminal code). In addition, it is a federal crime to take people over state lines for illegal purposes. But you don't become an emancipated minor due to parental divorce. You have to be officially emancipated by the court. If this woman had emancipation papers, then the above analysis would apply. If not, it's a bit murkier.
Leaving someone in an airport in PJs in handcuffs is a crime. Again, what that crime is called depends on the specific state and specific circumstances. If she is in fact emancipated, then you're looking at a kidnapping-type thing. If not, then it's a child endangerment/abuse issue.
But I just don't understand why she didn't ask someone at the airport for help. Methinks we don't have all the details?