So is a detailed written plan on how to build a bomb and sneak it on an aircraft.

That's not the issue.

I don't think the charts would be prohibited per se but I also don't think that the OP was wise in copping attitude with the TSO. Regardless of whether the individual is right or wrong it's never a smart move to pick a fight with an authority figure. What do you have to gain by doing this? AT THE TIME OF THE INCIDENT the guy with the badge invariably has the upper hand and you will come off second best every time. Once again I have to quote (well, ok, paraphrase) Sun Tzu in The Art of War "Never enter a battle unless you can win it and never start a war unless the benefits of winning the war outweigh the costs of waging the war." In this case the was no chance of winning the battle and the costs of waging the war probably outweighed any sence of moral victory achieved by this thread.

A simple, polite response would have been a better move in my opinion.

If the charts weren't of the route/area the OP was flying it shouldn't have been an issue at all. If they were of the route, a simple "I'm an aviation fan and I was curious as to what was in the area. Not much diffenet than the route map displayed on the IFE, really. Thanks for showing an interest in my safety. Have a nice day" might have saved him/her $15 and a bit of grief.

Not picking on anyone, just stating the facts as I see them....

Edit: Oh, and regards to the TSA "confiscating" things, what they will say (and I suppose they're technically correct although I disagree) is that they don't confiscate the items. You don't have to give them up but if you don't you don't fly. The decision is yours.