Where in the world do you get the idea that a Halachic state will require no army and no natural hishtadlus for protection from enemies?
If you reread my post you’ll see that I was MOCKING the thought that learning Torah is enough and no army is needed. So too vice versa.
And even the Gemara that you quote doesn’t seem to support your case. Yes, Dovid HaMelech’a Torah gave the zechusim for the army to succeed… But Dovid HaMelech wasn’t in Kollel 24/7. He was a warrior! A general! A king! This doesn’t support that we need Torah learners in Kollel while the army fights. This supports that we need Torah learners bringing their zechusim to the front lines!
What’s your source that Dovid always fought with Yoav? From Rashi it doesn’t seem that way.
Rashi writes on Tehillim kapital chof (which is said till today to daven for Jews in danger): This mizmor was composed because Dovid would send Yoav and all of Israel to war, and he would stand in Yerushlayim and daven… Our Rabbis say, if not for Dovid, Yoav wouldn’t go to war.