If he has the power, it doesn't matter how long it remains active. That's like saying Goku doesn't have Clear Mind because he's not in Ultra Instinct all the time. Secondly, Auto-Reflexes is a subpower of Autopilot, so trying to differentiate between the two so much is kind of a moot point. Saying a User of Autopilot wouldn't have Auto reflexs is beyond ridiculous. His reflexes would naturally be on Autopilot as well.
So far, Killua actually looks like a good candidate for this power.