Normally speaking, the price should higher than Variable cost + Fixed cost,
However, at special moment, employer has to keep the machine and worker busy even the price is not high enough, otherwise the loss will be much higher.
At these moment, Variable cost is the minimum requirement, meaning contribution is non-negative.

Decision maker is not kind of assume fixed cost is sunk cost, but has nothing to do with it.

For this reason, this action is treated as temporary tactics, couldn't last long.
It is ABNORMAL, should be avoided as much as possible.
I hope this helps.

短期