I guess they saw the polling numbers that showed Trump rising among Blacks. They are in panic mode.
Exactly. This is about the slow leak of black voters who are seeing their lives improve since Trump's election. They are hoping that Trump will attack Lebron, a popular and very high profile black man, so they can continue to shout that he is a racist. Best thing Trump can do is is ignore Lebron, and let him remain irrelevant outside of sports.