I presume they need to court more international money because downtown investment banking firms won't be the ones occupying large portions of it any longer.
They always needed to court government and international tenants because there simply isn't any need for all that office space in Lower Manhattan. And that was true even BEFORE last year's meltdown in the financial sector.
When they broke ground on Seven World Trade Center (the 52-story building at the north end of the site that also collapsed on 9/11) a few years ago, the only lease that was signed at the time involved the developer's own company.