Moonshine is not the only counter...
It is the only pilot tool to counter the gun, good counters are disable weapons, keep the gun disabled it'll not shoot you.
Mercury, Artemis, Hwacha...
Yes and no, your ship is continuously turned around (high ROF / reload time) and you will probably have just one gun pointing at the enemy ship (mercury is useless because you get out of firing window too easily, hwacha is probably the reason you got turned in the first place, meaning you cannot fire with that). One gun can help damaging weapons, but won't keep them disabled, not to mention that the enemy ship may have more guns than the minotaur alone pointed on you.
Merc works good when used in unison with moonshine.
Your argument that "Hwacha is probably the reason you got turned off arc in the first place" makes little sense...
Galleon Hwacha can disable well and the weight of the galleon means it is harder to turn off arc...
Spire Hwacha is not easy to turn off arc due to the ships profile.
Also the damage output of the gun means it is not a good killing weapon, giving time for pilots to recover during reload and to disables and do damage.
Yes the enemy may have more guns, galleon will have two or three guns pointed in your direction, two burst Artemis shots can disable two of those three guns, if you're on the side of the galleon with two guns and have an Artemis with a good gunner, you're laughing.
The Spire was buffed but is still susceptible to easy damage from a Hades, its a giant target which can be kept at a respectable range, kill it first or perhaps a mobula with Hades double Artemis and you can keep it disabled enough, get your allies to concentrate fire on the spire and you can still kill it quickly.
Now I'm not saying the gun is balanced, it is not, but it is not as overpowered as many claim it is, otherwise it would have been used much more during the SCS.... I didn't see one in the rounds I took part in.
The guns arcs make it harder to evade and avoid, if it catches you off guard it can put you in a bad position (for example a squid phoenix claw turn is hilarious if shot by a minotaur) but it can be countered...
Artemis is the saving grace, good range, good arcs, good disable power, just remember if you're intending to counter the minotaur on the enemy team with an Artemis, let your gunner know it is their primary target, if you need to explain where the gun is positioned on the enemy ship.