Greetings. One of the main problems with “organic” “blends” is that whats good & healthy to grow plants isn't necessarily safe for live animals/reptiles like tortoises. Lots of organic things are also toxic to animals - so the question remains what are the contents? A company can take all kinds of vegetation, tree limbs, manure etc & combine in a massive shredder to make an organic blended soil that might be good for growing geraniums, but unhealthy (or lethal) to a tortoise.
Be careful. Id switch to a known safe substrate. Good luck.