No the separating of the bananas doesn't slow the ripening process of the bananas.
In fact when I started separating the bananas I found that the bananas when separated actually ripened faster than they would when not separated.
Bananas usually last longer and stay fresher longer as well when you keep the bananas separated so if you want to keep the bananas fresher longer you should separate them.
You can also keep the bananas fresher longer by wrapping the stem of the bananas in plastic wrap and keep them separated.
Also do not refrigerate the bananas as refrigerated bananas makes them go bad faster than just leaving them out at room temperature.