1. They don't want abusive behavior included in their training corpus
2. Humans shouldn't exercise abusive impulses in general
3. We have no way of knowing when or if a model "feels" something
Of course item (2) is going to pull all the absolute sickos out of the woodwork who apparently find it very important they have as realistic a facsimile of a victim as they can find to exercise their cruelty. And item (3) will pull out all the Nobel-prize-winners-to-be who somehow know for a fact that models aren't and cannot be conscious (or moral patients).
But yeah, all 3 of those are far better explanations than some ridiculous multi-hop removed thing to escape consequences that they're already escaping and which would obviously create far worse legal constraints than the one you think they're avoiding.