TonyTilli said: "So lets flip it then: youd be super chill with a half-Black, half-white woman who looks fully white playing Rosa Parks?"
You do realize that Puerto Rican is a nationality, and African-American is a race, right? You can be Puerto Rican and have any variety of racial backgrounds. While I don't disagree that having a Puerto Rican actress who presents especially white would probably be more problematic in this context, getting upset about someone that still presents as brown and is actually Puerto Rican seems unnecessary to me. But, everyone has their own viewpoints.
Also, Rosa Parks was a real person, so having someone who presented as white play the role would be a problematic choice as that individual would have to be selected with the express intent NOT to cast someone that fits the part from an authenticity standpoint.