Short of total sterilization, mass extinction events seem to be really good at creating space for new forms of life to develop. In a way, preventing them in the name of the non-human life here is just picking the incumbent over whatever comes next. How would we feel if aliens stopped the mass extinction events that led to our existence? I’m not sure there’s solid argument for why one is more deserving of existence than the other.
I think why this slightly rubs me the wrong way is it feels like an excuse to make us feel good. Non-human life seems by and large indifferent to its long-term fate on this planet. Let’s not pretend we do anything significant for non-human life that isn’t to our direct benefit.
Just my perspective. Not trying to say “no, you’re wrong!” Just, “I disagree.” I’m going to guess there’s an entire named branch of philosophy that explores this.