It’s because this person is a moron.

They have no understanding of imperialism. The paper they are criticising is about unequal exchange in trade between global north and south countries. They think how anti-imperialists claim imperialism works is something like this: global south country harvests its natural resources to create wealth. This wealth then gets appropriated by the global north through unfair trade dealings.

So they posit that if global south countries just didn’t trade with the global north, they could just keep their wealth and prosper. So sanctioned countries would actually get wealthier compared to non-sanctioned countries. Since this is obviously not true, (their strawman of) imperialism has been debunked.