Correct, unless the Heroes had been captured in the same phase, then the Heroes would go to the LoB.
For example, if you have Raider's Camp and capture a Hero, but then I play Shipwreck later in the battle, the Hero would go to the LoB since RC would be negated first (before being discarded).
If a capture happens and then in a later phase or turn Shipwreck is played, the Heroes are discarded because the "place" happened in a previous phase and cannot be negated.