1.020 enough to form CO2 "blanket"?

I'm a new brewer, making a hard cider and i just bought a better bottle to transfer into a secondary. When i transferred i was paranoid about getting an infection so i threw 1/3 a cup of brown sugar in in there and took a reading of 1.020 SG, with racking will there be enough yeast/sugar to create the "blanket" of C02? I'm afraid of infection.

The co2 won't protect you from infection as much as it will help prevent oxidation. If you cleaned and sanitized well, you should be fine.

If it has fermented in any way it will always have co2 build up in the fermenter that's way we use airlocks. As yeast eat the sugar they fart out the co2. The CO2 rises in head space of the fermenter pushing out the O2 and pushes through the airlock.Same thing happens in secondary the CO2 will build up and push out of the airlock just way way slower than active fermentation. Dont be worried your cider should have plenty of alcohol to protect it from most infections. Keep your vessels sanitized when you transfer and soon you will have fresh cider to drink.