I disagree with your conclusion. I don’t think a piece of media can be toxic via the moral standing of its creator. If the content itself is toxic, then sure. To separate the art from the artist is to analyze and experience the thing itself in the moment, not the information attached to it such as it’s origin.

Now if we’re talking about supporting someone bad by buying their stuff then sure, you shouldn’t do that. I just wouldn’t frame it as the piece of fiction itself being bad. Consider piracy.

Take a great piece of fiction, say, Crime and Punishment. Now let’s say that it was actually written by Adolf Hitler. Will that shape your subjective experience of it, potentially even making it completely unpalatable to you? Yes. However, does that make it a worse piece of art? I don’t think so.