You're reading way to much into this.

Physical gold bars are transferred via plane between London and New York every day. The gold flies in the cargo holds of regularly scheduled commercial passenger flights. The quantity transferred depends on demand, and could be several metric tons daily.

This is nothing unusual. Dubai is another major gold transfer hub, and it operates via the same mechanism.

Regarding the article highlighting differing international standards for gold, London uses standard 400-ounce bars, while the US uses 100-ounce or 1kg bars. Often, the bars need to be remelted (elsewhere, typically in Switzerland) before they can be added to the vaults.

Again, nothing unusual.