Not GP but yeah I do feel there are some serious ethical problems created by the proliferation of humans and subsequent mass extinction event. Do you not?
Ethical problems being created by a scenario does not necessarily mean that you should not execute that scenario. Sometimes you're caught between a rock and a hard place, and ethical problems are created regardless.
There are ethical problems created by any conscious action. That doesn’t make sapience problematic per se.
No, I'm biased toward our species, and feel that our terrestrial diaspora helped us to survive, and an interstellar one would too.