It's nothing to do with racism despite what all liberals, progressives, anti racists, BLM, antifa, and democrats might say. They all constantly say everything is racist when they don't like something, something doesn't go their way, or when they want something.
He doesn't want a black pastor because they are disruptive and because they love attention so they will go out on the streets, on tv, infront of their congregation and shout and yell about racism and in effect be disruptive to the procedure.
He didn't say "no blacks", he said "no black pastors" because they are a problem.
You really should get off the racism bandwagon because it blinds you to reality and it also turns you into a single and narrow minded puppet that only sees racism and nothing else.