Need advice asap, spagnum moss or fluval stratum for half rotted corm?

Hi! I have a new baby variegated pink dragon and half of the corm was rotting. I had to remove half of it. The roots still look great and it's soaking in water with some peroxide atm. I want to repot her as soon as possible but whats a better medium for a half rotted corm? Spagnum moss or fluval stratum?