I couldn't find a specific clip discussing the half-life and dosage frequency of Saw Palmetto from the Huberman Lab. To get precise information and possibly the related study, I recommend reviewing the full episode where the topic of hair was discussed.
You can revisit the episode titled How to Optimize Your Hair Growth, Health & Appearance, which covers various aspects of hair health, including supplements like Saw Palmetto. This episode might provide the details you need for your email to the supplement producer.