Antialiasing helps lower resolution screens look smoother. A 13 inch Retina display has such small pixels (227 per inch) that you are unlikely to see any jaggy lines even with antialiasing set to 0x. Setting it to 2x might feel subjectively smoother, but it would be by a tiny amount.
Here is a screenshot from my 226 pixels per inch MacBoo Pro, where one line is at 0x and the other is at 2x:
I set the scale of the image in this post to 50%, which then makes it look like it does on my screen. You can open the image in a new browser window to see what is really going on.
It would be interesting for you to text at 2x too, to check if it is that there is any antialiasing, rather than say if it was 4x or higher.