Call shy doesn't necessarily mean they don't vocalize. It simply refers to that they have been called to by humans way too much and that they are starting to be distinguish between an imperfect call and a real hen. But call shyness shouldn't be a showstopper either. Sometimes we simply have to when to call and when to shut up. Remember, not calling is just as important as calling.

There are too many factors to know why that tom walked away. Did you have decoys out? If he heard a hen but didn't see one, he might know something is up. Did he see you or something else he didn't like? What calling techniques did you implement? Turkeys tend to have a different language at different distances.

Most of the time, turkeys will not do what you want them to do unless you use mind control, and that won't happen. Sometimes we simply have the perfect setup and a turkey will walk away. Other times we can end up doing everything in the book wrong and end up filling a tag. Some say turkeys are extremely smart, others say they are the dumbest animals on the planet.