That appears to support his point, as there is exactly *one* tower with more than the WTC's 110 floors built since 2001. The others are deriving height from "ornamentation".
Actuallly though, I have a theory. My guess is, compile a list of possible tenants, big names who need class a space and can afford high price rents Figure out when these tenants current leases expire. Coordinate construction and completion to maximize leases coming up for renewal. Make your sales pitch. Hence, no rush to build anything at ground zero.