If they answered with the truth, their lifespan would decrease. Although World Emperor/Divine Kingdom lifeforms had very long lifespans, they would not be able to triumph over the continuous reduction of their lifespans.
If they answered with a lie, their soul energy would diminish.
Once a lifeform's soul was harmed, it would entail a grievous root injury.
The stronger the lifeform, the more challenging it would be for them to heal from a soul injury.
Hence, when powerful lifeforms suffered soul injuries, most of them would decide to negotiate with their opponents rather than continue battling it out.
If they continued battling it out despite suffering soul injuries, it would mean that the two parties were either irreconcilable enemies or fighting over profitable resources. The profits had to exceed the impact of the soul injuries.