Phoenix doesn't use guns. There goes half that reasoning. Plus, he doesn't even normally carry one.
You keep throwing "NLF" around when we have sustained why the Luck would actually work with examples from the game itself. Even going as far as using headcannon saying Makoto's luck will "run out", when not only the game supports otherwise, it isn't how it works in the first place.
You also keep throwing "outside help", that means nothing here. As per SBA, they are fighting in central park, there are other people, using your arguments, boosting Makoto's luck as "it relies on it" (let's ignore the broken door, the fact that he even got to enter the school, Junko's stuff, etc).
For the final time: Makoto can't hurt Phoenix, and even if we say Phoenix can hurt Makoto back, his luck will save him in the end. Inconclusive.
Edit: BTW, when I said that Makoto's durability was on par with Phoenix, I meant Phoenix's AP. Which doesn't even change my reasoning, as I've even said that even if we say Makoto will get damaged, his luck saves him, as has saved him all the time in the game.