He didn’t compare the two because they were equivalent in nature, but because they were near in size.
No, things measured in different units are not comparable in size. The “comparison” is like marveling that the distance between two cities (in miles) has approximately 2/3 the value of the speed-limit on some road in miles per hour. If the road connected the cities it would tell you that it would take about 40 min to get from one to the other, but otherwise it’s silly.
(2/3)*(NZ GDP in US$/year)having approximately the same numerical value as Facebook’s market capitalization in US$ is a pointless “comparison”.