No, I don't think Atkins is a low GI diet in any phase. A low GI diet does not seek to alter macronutrient composition, meaning it stays within conventional recommended guidelines for consumption of fat/protein/carb. It only asks people to select for their 65% of carbs things like whole grains instead of refined grains, brown rice over white, fructose over sucrose, etc.

Atkins in maintenance is still definitely carb-restricted, even for someone with very low metabolic resistance. I am in maintenance and I consume only 20% carbs on average (slightly less or above that). Granted my metabolism is not like most peoples, but I think the average maintainer isn't ever going to approach the high levels of carbs that you will consume on the low GI diet.