It's not that the teacher were racist. It's that the tests or indicators used to identify individuals as gifted were not evaluated well enough for bias. It's not overt racism. It's stuff like rich parents hiring tutors and the rich parents being more likely to be white (I would argue that implicit racism isn’t racism as it lacks intent, but is still a harmful bias to be eliminated). This goes back to their comment on high achievers getting into the program vs the inherently gifted. Another example is IQ tests administered in English to students who have English as a second language. Even stuff like parents training their kids for the format of the IQ test questions provides and advantage.

The problem I have with a lot of the stuff related to gifted learning is how it's structured and gate kept. In a public school, there should not be a limited number of seats for an academic program. Any student who can perform in that program should be allowed to participate, not just the top 10% or whatever. I think it should be measured on their current academic performance, not some IQ test or teacher recommendations. If you're consistently getting As in the regular course, you should be eligible to try the accelerated program. You may get more out of the accelerated program even if your grade drops from As to Bs. It also seems that many programs are all or nothing - either you're in the gifted program for all subjects or none at all. Being advanced in one or two subjects and in the regular classes for the others should be fine. It seems this is at least picking up more popularity in the past decade or two.