Swelling in one leg from below gastroc to ankle. MRI norm. NCV/EMG returns pinch nerve. Was told pinch nerve doesn't cause swelling. What to believe?

You're right. A pinched nerve might make you FEEL swollen, but it doesn't produce any swelling. Something locally is going on down there that's causing the swelling like a clot (phlebitis) or a localized source of inflammation, like tendonitis, myositis or even a stress fracture.
Pinched nerve. the nerves that run to the lower are motor, sensory and autonomic. motor - muscle control, sensory - touch, pressure, etc. Autonomic - temperature regulation, sweating, etc. It is very possible that the pinched nerve could cause the swelling in your leg.
They don't. A pinched nerve does not generally cause swelling. But your leg may feel to you like it is swollen even if it is not. If one leg is larger than the other, or red, or warm, that is more likely due to an infection or to poor circulation, or a blood clot in the leg. See your doctor if that is the case.