I reread the article with a little more care and as a result of special relativity the satellites "fall behind clocks on the ground by about 7 microseconds per day" and as a result of general relativity "each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day". So that would mean if the ISS was orbiting at the same level as the GPS satellites the astronauts would age faster, but since the ISS is closer, they age slower.