What an achievement it would be, to make the most decent of a tribe of liars start to use lies to counter lies, in order to defend truth, by forcing them against each other.
What a division it would make, to force these masters of undying hatred battle each other by making the most basic of natural facts an enemy to them. To use their own self interested deception in order to fight deception itself.
And, to those that defend decency with lies, you owe nothing... for they did it for a reason no nobler than their opposing counterparts. They never took on the cost or any responsibility, or else they would not have lied.
Lying to defend truth is not uncommon.
Typically, one is defending ones or another's perception of the world from manipulation.
The purpose is to maintain their health.
The management of another through sympathy because seductive lies turn them further into weaklings and this is known. The taking away of a lollipop from a child. Telling them some bullshit explanation they'll listen to or comprehend, because the truth is too unpalatable. Maybe even classified as hyperbole.
Perhaps lying to a NSDAP officer about some Jewish kin in the attic would constitute something equivalent.