Thanks for sharing your experience. Seems to confirm "as high as possible without rocking the hips"? Like you I also like to move around. Most cyclists I see on the street can stop at the red light staying on the seat with one foot on the ground, while I was busying with dismounting and mounting (this is Manhattan with a red light every few blocks).
Having the seat this low is fine for basic riding around at a leisurely rate. However, if you do any long-distance riding or anything with higher-intensity than 25%, you'll end up with knee problems. Knees can safely transmit the highest loads when they are straight, bone-to-bone. Bent-knees transmit loads through the ligaments. And when bent, they have a lot of wobble and will load the ligaments unevenly.
Even with a rotated "comfort bike" position, seat-height should still be the same (seat to pedal). Close to full leg-extension at the bottom of the stroke to keep the loads off the knee ligaments. There's various online guides to
measuring seat-height and adjusting it optimally. They all will place your seat-height at about 100-109% of your inseam. It's typically safer to be on the too-high side rather than too-low as knee and hamstring injuries aren't as common with extra height as it is with being too low.
As for red-light stopping and starting, you'll find with practice and experience, that getting off and on the seat will actually be faster. Stopping is irrelevant because whether you get off or stay on the seat, there's no longitudinal travel anyway. Starting off the seat with one foot on the ground and one foot in the pedal with crankarm up & forward lets you transfer ALL your weight from the ground foot to the foot on the pedal. This is an instant 0-3mph jump with just half a pedal-stroke and you're across the intersection as the other folks are tippy-toeing trying to balance themselves on the seat trying to shift their weight from the ground foot onto the saddle.