Book publishing through publishers is old model.
Esp. if publishers are so yellow livered. I have no use for them.
Publishing houses edit books, give advances, provide some ad and promo support. Still the preferred way to publish — if you can.
(Self-pub books are often an unreadable mess.)
This book might well be published by Regnery, an excellent house that’s been publishing conservative books for more than 50 years, with many on the bestseller list. Soldiers’ agent should know this.