The freeze opponents option only works on opponents close to you. So when you pass them far enough they start moving again until they get close enough for the trainer to freeze them. But if you're too far behind when you turn it on, you'll notice they won't be frozen then either. The Spin-Out option seems to have a much much larger radius, so use that to help catch up, or help you leave them farther in the dust.
--------------------------------------------------------------------------- Unwinding is the mortal coil, that drives the gears to tick and toil, until at last, it rests, unwound, and we lay silent in the ground.