When someone says “I agree with Colin Kaepernick’s point but he should have made it differently,” it’s a way of appearing to critique a protester’s method only, and not the substance of their position. But it strikes me as a veiled way of saying something very critical about the substance of their position. In essence, the speaker is saying “Social position P has merit, but protest method M comes at a moral cost; that moral cost is too high to be justified by appeal to the moral and social value of P.”
In this case, P is the view that black life is held cheap in the U.S. and that the taking of black lives by agents of the state is too readily accepted and rationalized. M is remaining seated during the national anthem. What are the moral costs of M? Fill that in how you like–at the end of the day, the critique is that the moral costs of sitting during the national anthem are so high that appeal to the value of black lives, and the accountability of state agents who kill black people, can’t justify those costs. That’s a commentary on the value of black lives.