I said what I said above based on 30+ years of experience in this field. Be aware that the entire field of gene therapy was paused for 20 years because a single patient died in a single study in the 90s.

Race is a proxy variable for genetic history and we have enough genetic history to identify what "race" people belong to, in a computational way, with a great deal of human judgement. Implementing that "logic" in the form of a gene therapy delivered as a virus is much harder. Molecular logic, these days, is fairly simple and doesn't allow us the level of accuracy you would need.

If you don't require 100% sensitivity and specificity the job is "easier". For example, what should your theoretical virus do to people who are children of two parents with very different genetic history? Which "race" do they belong to? And if you go down that path, you're basically going to have to convince your funders (because this would be an extremely expensive research project) that your weapon of mass destruction will likely kill some fraction of allies.

Those are just a couple things off the top of my head; I could write a whole book on how hard delivering gene therapy is.