Whether you like it or not, racebending Bruce especially in this really divided political time would bring up a lot of controversy that I think WB and Matt Reeves would rather not have. There's zero chance they're gonna do that right now, it does add a very obvious subtext in a lot of people eyes, both from people that like the idea and those that dislike it. I imagine that if a filmmaker wants to make a noir driven detective Batman film, he'd probably want people to talk about well, Batman. Not talk about asian representation or whatever, not that there's nothing wrong with bringing those subjects on a film but Batman is really the wrong character.
And Matt Reeves also doesn't seem to like to make his films political even in sutext. He really had a chance to go political with the Planet of The Apes films and he intentionally avoided it.