There isn't a moral equivalence between interfering in the process and allowing nature to run its course.
Argument from naturality. The moral equivalence arises from the context and circumstance - not on whether one chooses to interfere or not.
Inaction doesn't require justification unless action is obligatory.
The decision to help a child mutilate himself is never obligatory (or even justifiable).
There isn't a moral equivalence between interfering in the process and allowing nature to run its course.