Not "make up" so much as "perhaps misremembering and naturally exaggerating."
Anyway. I know what scene they're referring to in that article and it was very obviously chroma'd but there has been also very obviously shot-on-location stuff in New York City as well this season, much like there was in Washington DC last year.
Obviously the majority of stuff was done here in L.A., but one chroma-keyed sequence of a helicopter chase hardly indicates that they didn't do any location work in the Big Apple.
For the first 8 episodes of season seven, 24
only spent a week filming scenes in Washington, DC. After that, the writer's strike happened, and I don't think they ever returned to shoot more material for the remainder of the season. The scene between Tony and Jack at the reflecting pool, for example, was done entirely with green screens.
Everything I've read has indicated that a similar shooting schedule with only a few days in New York City was followed this year.