Where have you experienced this?
Isn't security an relatively separate system?
Yes but, I've been in LGA/JFK where they took your boarding pass and stamped it with expedited.
But most times you go to a lady and show her your TSA, she allows you to go through the expedited line.
Now let's go through with that, and I get to the guy who scans your Passport and boarding pass, if he should realize, then yes I can say oops wrong line.
Now only thing needed is to find a flight which leaves from the same terminal and security check point.( I'm sure I can find it online or the airports website.)
Yeh I think it's easier to just wait in the line.
Would play around when I'm flying and not doing this for someone else.
Just to much info to give over when it's not a concrete idea.