The underrepresntation of black people in tech isn't "racist" though there are probably a lot of racist actions taken place that led up to it, and of course tons of structural racism that cause it long term. But the discrepancy isn't "racist" in itself. It's just a discrepancy.
Well of course it is, but it's inaccurate to suggest that the gender disparity in tech is entirely attributable to companies turning away female applicants on account of their gender. And if the suggestion was for some hypothetical company that was doing that to stop, there would be no objection.
The problem comes when the portion of the gender disparity that isn't attributable to discrimination is attributed to it anyway, and then employers are continually lambasted for something they didn't actually do.
It distracts from addressing the real problems (especially at the high school level) that could actually improve the gender ratio going forward.
And that's why no one makes that argument I hope!
Suppose that height is an advantage in basketball and we thereby discover that asian men are underrepresented in the NBA. Are you claiming that is racist and something we have to do something to change?