Send your in laws to Ford, Holden or Toyota to see how these cars are built, that happens to almost every car that comes down the production line.
But Ford shouldn't have let them see what they were doing.
I agree with you completely and have done this "minor adjustment" many times myself under warranty but what got me was the arrogance of this guy to do it in front of us and tell us they do it to all of them.
Not a good look!