The test itself is not racially biased. It is the vessel through which examiners can project their beliefs. Therefore, it is no more vulnerable to racial biased than a jury of the defendant’s peers might be.
The existing judicial system is racially biased; however, this is because racism is still in existence in wider society. No legal tool will be protected from individual prejudice, be it trial by jury, lie detectors, expert testimony, or non-jury trials overseen by a judge, as long as the margin for human error exists.
Given a polygraph test’s proven ability to determine lie from truth at a better rate than behavioral analysis and guesswork, it’s evidence should be admitted in court under the understanding that any method to determine guilt is vulnerable to individual prejudice, but until we can remove the margin for human error, we cannot escape this.