I think that people who say that Starfleet is not a military organization must just have a different definition of "military" than I do.

In addition to all of the things you mentioned, when Earth is attacked, Starfleet frequently orders ships to return and fight.

So, they're either a police or a military, and the fact that they may face court martial for disobeying orders to fight really decides it in the direction of military for me.

That's by my own definition of military. I was looking at the Star Trek wiki and it seems that Roddenberry was very much against Starfleet being the military. He must just have a different criteria.