Yes it is and according to what you linked to "According to Lokeshwar, potential causes for these declines could be increased obesity/BMI, assay variations, diet/phytoestrogens, declined exercise and physical activity, fat percentage, marijuana use, and environmental toxins."

Tucker Carlson is using it as a very thin excuse to basically make a series about how men need to be more like a particular cultural concept of men. Here's the trailer for "The End of Men" nowhere does it mention that study or a testosterone drop. Maybe the show itself touches on that but in my opinion that would only be so people like you could justify what is basically a propaganda video for right wing masculine culture.

https://www.youtube.com/watch?v=IcxLQeh6J6A