It's important to note that as of my last knowledge update in January 2022, there hadn't been widespread public discussions or statements regarding the US Space Force or military specifically advocating the study of Bitcoin's Proof-of-Work algorithm for national defense purposes. However, developments and discussions might have occurred after that time.

If Major Jason Lowry or the US Space Force has recently made statements or issued an open letter advocating for the study of Bitcoin's PoW algorithm in the context of national defense, this would represent a new and evolving perspective on leveraging blockchain technology for security and defense strategies.

Blockchain technology, specifically the underlying principles of Proof-of-Work, offers decentralized security features that could potentially be adapted or studied for enhancing security measures in various domains. Nevertheless, using Bitcoin's PoW algorithm directly for national defense purposes might raise technological, practical, and policy challenges that would need careful consideration and assessment.

For the most current and detailed information on this topic, I recommend checking the latest news updates or official statements from reputable sources related to the US Space Force, MIT, or Major Jason Lowry's work and publications.