Is the tank always friendly?

I've been playing through the game and had gotten all five main endings, and started with a new save file. I noticed that after the first play through, the Goliath Tank in the Amusement Park wasn't hostile starting with the second play through, even before I got endings C, D & E. Going for ending A, I've noticed the tank wasn't hostile.

My question is, is the tank initially hostile, or did I just blindly attack it because another machine said it was dangerous beyond where he was? I think it may have been hostile initially, but because the game does save data outside of the save files which seem to affect it even if you were to remove all the save files, I'm no longer certain.

The tank is always an optional boss, regardless of route. It is actually not hostile, like the rest of the amusement park machines. During my first run of Route A, I, too, attacked everything on sight before realizing the machines were not attacking me. The tank is the same way.

However, if you want 100% Unit Data Completion, you'll have to fight it at least once. The tank will also drop a Machine Core, which you can sell for quite a bit of cash, if you need that.

It isn't hostile initially.

Like most other machines in the amusement park.

9S clearly asks you to attack it the first time you see it if you seem to get away without attacking it. But that's it.