The author’s point is that labeling someone as “lazy” is intellectually lazy. Every person, throughout their lives, exhibits behaviors ranging the full spectrum from lazy to diligent. They might be lazy about one thing but diligent about another, all at different times, for reasons others may never find out about. Labeling a person as lazy ignores all of that, and lays judgement based on a specific things the labeler wish the labeled was more diligent about, and at the time of their choosing. It’s entirely subjective, and rarely constructive. Laziness, as a description of a person’s measurable, inherent attributes, is inherently vindictive, intellectually lazy, and generally unhelpful. It’s a way of saying “I give up on you, I don’t want to know your story, and I think you can’t change” without acknowledging your part in that judgement.