I think that's the key. I didn't like or re-blog the original post, so I have little hope of every finding it again, but if I recall correctly it was rhetorically set up so it was like, "Do write PoC characters, don't write stories about being a PoC," etc.

If you aren't yourself a PoC, your PoC characters can be PoC, and their being PoC is going to be a part of who they are, but that story, in the hands of someone who is not a PoC (and more specifically, not whatever specific ethnic/racial heritage that character is), should probably be about literally anything else that PoCs do besides, well, be PoC.