Utility-rec.709-camera as diffuse texture

Yes because you are trying to solve aesthetic issues at a place in a system where it is not really ideal to do it. What are you going to do once you mix your textures with properly acquired Scene Referred textures? In ACES if you need to introduce a creative look modification, you should really do that with a Look Modification Transform (LMT): LMTs Part 1: What are they and what can they do for me?

Cheers,

Thomas