Her definition of "avid texter" comes from the perspective of a woman who grew up without texting. So we don't know how often he was really texting; the police know of course.
As an aside, about his short messages during the exchange with his friend: his friend was also sending short texts until DR didn't show at 6:30am. I don't think that means anything.
Have you asked her this or seen anywhere that suggests this ? ty
av·id - . Synonyms: enthusiastic, ardent, keen; devoted, dedicated; zealous, fanatic
That does not try in with what you are saying