That's kind of his point. Even if you have absolute certainty about the factual accuracy of the tip, it skews law enforcement towards what is essentially discrimination by selective enforcement. Throw in uncertainty due to latent racism in the witness, poor lighting conditions, or a general bias against minorities and you've got the perfect storm for a discriminatory justice system incapable of fairness at all levels.

How does having absolute certainty about the factual accuracy of a tip equate to discriminating law enforcement?

That isn't even remotely close to what I said.