The line you are riding is your line - whether it's the right line or not- and the overtaking rider has the responsibility of getting around you cleanly, withing the rules of your group, and without spooking you or making you alter your line. The caveat is that you need to make sure that you don't make any sudden moves to alter that line.
Get a CR to help you learn the line and then try to ride it consistently. If that line takes you white line to white line, even if you really aren't carrying enough speed to need all of the track that's fine. As you get faster you'll need more track anyway. To the guys who see this a problem, you just really need to work on overtaking. This has never, ever been an issue for me, and I can go out there and work my way though traffic without any problems. I have always tried to use my time on the racetrack to focus on learning, and learning how to pass is part of that. I have no special talent for riding a motorcycle so most likely you aren't any different than me. The only difference between me and some other riders who have a problem with this is experience; I learned how to do it and so can you.
When I see that a rider is taking a line that is setting him up to use all of the track on the exit I just plan my pass to go by on the inside at the exit (withing the rules of the group. Yes, you can time your pass so that you both are straight up and down), I call it an outside, inside pass. The opposite is true when a rider is holding a tight line through a turn; then I use an inside, outside pass. You adjust your own line to either hold a tight line, or take a wide exit based on what the rider in front of you is doing. You can judge that almost 100% of the time.