noun
1.
a false statement made with deliberate intent to deceive; an intentional untruth; a falsehood.
Synonyms: prevarication, falsification.
Antonyms: truth.
2.
something intended or serving to convey a false impression; imposture:
His flashy car was a lie that deceived no one.
3.
an inaccurate or false statement; a falsehood.

Under the first definition, probably true, because it requires an intent to deceive, and a person incapable of telling the difference between truth and falsehood would not intend to deceive.  However, under the 3rd definition, there is no doubt, as the person in question has definitely uttered false statements.  But correct, there is nothing to be gained by truthful accusations followed by dishonest defenses.