I probably said something like that sometimes going to 2 hands makes sense and that only 1 ace remaining (in single deck, I assume) is not the determining factor. The most common reasons are other players at your table when the count is high and playing the final round of the deck/shoe when the count is high. I may have also said that you can get the same EV with less variance or more EV with the same variance when playing 2 hands and that 1 ace remaining has no direct bearing on this.

The decision is based on your advantage and the other factors mentioned above. Specific rules like No Das and only double on 10,11 are not directly related to the decision.