I assume the title is designed to be a bit provocative. But I think he makes a few claims:
Big Five personality (especially neuroticism and extraversion) explains self-esteem well.
It's very difficult to change a person's fundamental level of neuroticism.
Interventions that focus directly on increasing self-esteem in a way that are detached from reality may ...
Turf war mixed with artificial distinctions. Behaviorism can hardly be considered outdated when the most popular therapies are behavioral: CBT, DBT, ACT. Even modern implementations of mindfulness are behavioral. Behaviorism is also popular in performance management and organizational psychology, addiction, instructional design, etc.