I think it depends on your horse.
My former horses were all good with stalls/confinement. My last horse LOVED her stall. My current horse hates his stall and needs his turnout. Keeping him inside is not “stall rest”.
That said, I’ve experienced situations such as yours. If the swelling is gone and the ultrasound was negative and the horse was always sound, I’d return the horse to the normal turnout schedule. I’d also start riding again and ramp up the work with real care.
