Regarding your first paragraph: I was operating based on a very loose hypothetical question that you posed. So, I think you're unintentionally strawmanning me here a little bit...
As far as the second paragraph is concerned I see your point. However, I specifically said life had to consume other organic material to survive, but not necessarily kill in the process. At some level of the food chain it does ultimately become a necessity though, and I do not see that as an ethical dilemma per se.