>>3611069He is right, he just worded it badly.
The exposure stays the same regardless of crop factor, the less noise on a FF sensor compared to an APS-C sensor is related to the 2.25 x more total light the full frame sensor gathers, aka signal to noise ratio.
You can view an APS-C sensor as a crop on a FF sensor (hence crop sensor), if you go into crop mode on your full frame body you don't suddenly have to change your exposure.