It shouldn't be killing them, that's a bug. But i just remembered that while testing i made the capsule remove the health management pixy flag so that could be why.
I don't see the slight depravity lowering as an issue since it allows you to use capsule on anyone...
...BUT thinking about it now if you use it then fill the meter elsewhere and repeat you will infinitely add depravity traits to a slave which could be a problem.
Here is an edited version that doesn't change the flag and doesn't remove depravity if it is full
I haven't tested it so reply me if broken.
View attachment 3303908