This is pure speculation, but I suspect the corruption there would be less likely to damage the artifacts - instead by delegating control of the plates to his brother the director was giving his brother a large amount of leverage to get a good position or decent cash payout out of the national Nigerian museum in Lagos mentioned in the article.

I'd be more concerned about those items going to private collectors, since they're probably safe for a generation and then likely to be scalped by the heirs for cash.