Is it better for straight, white males to only write about the experience of being a straight, white male? Why limit yourself to race, sexual orientation and gender? You mentioned sexual abuse. What about verbal abuse? Should a writer who has never been verbally abused be allowed to write the experience of a character who gets verbally abused?
Unfortunately, we don’t get to decide what makes a person who they are and saying what a person can or can’t write about based purely on how they were born is doing nothing to help people understand each other.
By your logic, people should only ever be allowed to write autobiographies as any experience that a fictional character has is simply a mockery of anyone who has actually had this experience.
In my eyes, the only solution is that people be “allowed” to write whatever they like and, if they misrepresent something, then that is a discussion (not an argument) to have. Anything else is just stopping the conversation before it begins. Burning the book before it was read, if you will.
Communication is always key. Shutting communication down is never the answer. People always have the right to say what they want. If you dislike what they say, it’s your job to talk to them and help them to understand why. Not ban them from saying it.