Who are Western museums guarding African artefacts from?

Title: Who are Western museums guarding African artefacts from?
Author: Christine Mungai
Media Outlet: Al Jazeera
Publish Date: December 3, 2018

“(…) Furthermore, the argument for "proper preservation" betrays a carceral ethic that should not be left unchallenged. What makes us believe that sequestration and preservation are unequivocally good? For some of these objects, their circulation in the community, and their inevitable decay and replacement is part of their cultural value.

Another argument is that "rich and secure museums around the world are the guardians of culture for those cultures which are not developed enough to reliably preserve and protect their antiquities." 

I wonder who appointed those museums  (and the white cultures they exist in), "guardians of culture", and more importantly, who are they guarding it from?

The tendency for whiteness to universalise itself and elevate its own cultural specificity as a stand-in for humanity's collective heritage has devastating consequences for those who find themselves outside it. It creates the absurd situation we have here, where people are seriously arguing that the cultural artefacts need to be protected from the very cultures that created them.”