In theory? It’s all about traceability and consent, preferably with a third party auditing system. A good skull salesman should be able to provide you with documentation of the origin of your skull and the consent obtained, as well as a contact at their third-party auditing firm. if the skull is fair trade, they should also be able to provide evidence that they are paying above market rates for their skull harvesters.
That’s all his financiers hear.
That’s all his voters hear.
Everything else goes in one ear and out the other, muddied up with enough “whataboutism” and “both sides” rhetoric from the financiers to keep the voters from actually considering alternative options.