"Taking that into account" IMHO means acknowledging that concept of tribalism when making long-term policy, when looking at what specific problems you want to solve with what means.
One part of anti-racism is establishing principles that allow "tribes" to coexist and treat members of other tribe fairly. That's all the anti-discrimination rules, requiring commerce and employment to happen on fair principles for outsiders as well; that's all the control of violence, hate speech, threats of violence.
The other part (or is it a different direction?) is to try to form a single tribe - unification, assimilation, rallying together against an external threat, general acceptance etc. "Building a nation" if you will, reducing differences and establishing national unity, though often at the cost of some international tribalism.
If we look at the specific situations described in the original article, it seems to me that there in most of them there are no "racist acts" (violations of the first part) involved, this story (unlike many others) does not involve the "other tribe" acting horribly against the members of "his tribe" - the article focuses mainly on the fact that mr. Diallo is not treated as a "member of this tribe", and provides many illustrative examples of natural emotional pain and alienation caused by being treated as an outsider, even if outsiders are treated fairly.
And that's conceptually very different. It's reasonable to mandate fair treatment for everyone. But it's not reasonable to mandate every tribe or subtribe to accept someone (especially because usually "the tribe" is not organized enough, it's effectively a sum of individual decisions) - freedom of association is a quite fundamental thing, it's completely reasonable for someone to (for example) treat only their extended family as "their tribe"; or for someone to treat only members of their particular religion as "their tribe", shunning those familymembers who are not. It's a free individual choice. It's worth noting that if you look at any list of prohibited discrimination types, then there's a "tribe" in almost all cases. People can and will treat someone else as "not my tribe" for all kinds of reasons - political beliefs, sports team preferences, having not seen (or not liking) a particular TV show, etc, and that is their right. You can't mandate being friends with someone; it's permissible to treat Bob as an outsider just because Bob is kind of an asshole, and it's permissible to treat Bob as an outsider just because you are kind of an asshole and hate him for no good reason.
You can implement various policies to try and slowly erode factional/"tribal" differences. But you can't eliminate the tribes or determine their membership. If (for example) Montagues and Capulets hate each other, you can't mandate them to stop that hate. If someone from the Montague "tribe" wants to marry a Capulet, then you can (and should) have policies so that they can marry despite the wishes of the tribe (if they're adults, unlike Romeo&Juliet), however, if the "tribe" wants to expel them because of that and treat them forever as outsiders, that's their right which can not (and should not) be prevented.