I think baseline it should be tuned to be statistically accurate. The problem is that people leave a lot in their prompt to be implied. Some interaction designers use this as an opportunity to infill their own subjective opinion of what should be inferred as a way to 'take care' of the user.
This isn't their only option... they could also just ask for more information.
A good approach here would be ask the user to further clarify what exactly they want before generating a person — "Do you want a random depiction or a specific depiction". A good tool for users is one which helps them be and feel more tactically or predictably in control of it; which means making them aware of its behavioural pitfalls so they can avoid them if they want to.
This isn't their only option... they could also just ask for more information.
A good approach here would be ask the user to further clarify what exactly they want before generating a person — "Do you want a random depiction or a specific depiction". A good tool for users is one which helps them be and feel more tactically or predictably in control of it; which means making them aware of its behavioural pitfalls so they can avoid them if they want to.