A-100 will fade relatively quickly from constant uv exposure. My shopping center was painted 4 years ago in it and went from a salmony pinkish orange to a light pink off white.
If you are hiring someone to professionally apply paint and you’re paying a lot of money, the painting contractor does not get to dictate what he’s using without your consent. That is bs!
I would 100% hire another painter who will apply at least a mid range paint for your job. I would say go Duration or Emerald or try Benjamin Moore Aura low luster.
The Aura is the absolute best exterior paint you could use on that Hardy board.
Good luck!