This is very well-reasoned and although you don't provide any comprehensive empirical support for children being color-indifferent, it largely comports with what I've heard and with my experience.

However, there are two other possibilities that you don't address that could change one's conclusion.

First, it could be that there is a good deal of implicit racism and children are sufficiently attuned to pick it up and internalize it absent any explicit instruction. If this is true, there could be nothing overt ever, and yet everyone would grow up racist. Implicit racism would be a stable and pernicious norm. One idea of how to combat this would be to explicitly pay attention to race so that you can explicitly reject these implicit cues.

Second, it could be that the world provides biased experiences (e.g. due to historical accident) that result in racist outlooks. For example, if children live in an area where almost all homeless people are black, they may associate blackness with homelessness; if they live in an area where most violence is from gangs of black teenagers, they may associate blackness with violence. If the attitudes they pick up on the basis of their experience are sufficiently strong, they may serve to perpetuate the situations that led to the disparity in the first place. ("I don't trust him...I'll hire someone else.") Again, an idea of how to combat this is to explicitly pay attention to race so that you can explicitly decouple the race from the condition instead of allowing intuition to link the two.

Are these things true? Are the solutions effective? These are what you would need to argue against in order to have a complete case (i.e. at least one of the two must be "no", because if both are "yes" then Kendi is on the right track).