Regardless of anyone's personal take on Kal-El being a POC, objectively this reeks of a PR move of one by WB and honestly this will likely backfire at the box office.
Whether anyone likes it or not, changing Kal-El is going to draw a big backlash. Some racist, some who are upset by changing the source material, some who feels it's pandering, and of course the Snyderverse/Cavill fans who are insanely loyal.
There is still a large generation of people who think of the traditional Superman. It's just that way. Given his iconic status, it's going to draw backlash. Even based on the stuff I've seen online, there is a segment of the African American community that do not like this and feel it's insulting to them.
It's not a big story right now because nothing is confirmed, but simply based on the initial reactions, I cannot see this going over well, which is why I think MBJ chose to distance himself from this.
If WB is going to insist on Superman being a POC, they are much better off using a an alternate character, which even then will have it's own unique response.