That's default for rocks and such, but not living things, whose existence requires by default the death of other living things
If you're going to talk about morality and agency, it is not a positive choice to eat anything. It's acting out of necessity to survive. Choosing not to eat is self-destruction and there is absolutely nothing about that that's a moral choice. In fact, it's generally accepted to be immoral[1]. This is why we force feed people on hunger strikes and why suicide is illegal. Modern/western written law is based on natural law.
"Breatharianism" is pure stupidity/insanity and anyone who undertakes such practice can (and will) literally go die.
We aren't talking about what the law dictates, we're talking about how some moral system might inform our actions. Two very different things, although of course the relationship between them is fascinating in its own right.
Downvote me all you like Andrew, but I'm going to call you out for espousing ideas that can literally kill people.
I'll leave you with this quote of yours to consider:
> Choosing not to eat is self-destruction and there is absolutely nothing about that that's a moral choice. In fact, it's generally accepted to be immoral.
If something is immoral, there must have been a moral choice made to engage in the immoral activity. "Moral choice" here is a technical term which means the choice itself has moral weight, not that the choice is moral.
I don't personally subscribe to this.
The default is not eating meat because the default is not eating anything. Humans must take a positive action to eat something.
Generally perfect duties in the Kantian sense take the form of "thou shalt-nots", so a positive action you shouldn't take, like killing a random stranger or some such. This is contrasted with imperfect duties, which are things that are merely virtuous to do - like using your time & resources to help the less-fortunate, for example.