BD has one-way pricing on most of its fares (except long haul). The fare isn't dependent on having to fly both/all sectors, so failure to fly the first sector doesn't trigger a re-price or cancellation.

I have no idea if this also applies to redemption tickets but if it's a BD short-haul I don't see why it would be a problem.

In any case, I thought the received wisdom on this board was that you should always book redemption trips as two one-ways so that you don't have these issues if your plans change.