The term “weed” has no formal scientific status at all,

Sure it does. It’s not astrophysics precise (because biology in general is a “soft science” in many regards), but it has a meaning when you talk about it in the domain.

In botany, a weed is a general term for any plant growing where it is not wanted. Weeds interfere with human activities and compete with crop plants for water, light, and nutrients.

Some weeds can later be found to have previously unknown benefits and be removed from the category, while other cultivated plants can be transplanted to new climates, escape cultivation, and become weeds or invasive species. Thus, the category of weeds is ever-changing, making the term relative.

The general term for the first sentence is what everyone uses colloquially. But the reasoning for it being unwanted is not “because it looks weird”. an otherwise “attractive” plant (like grass) can be a weed in some other context if it’s taking nutrients from more ecologically valuable plants.

It’s ethics and morality applied to a specific situation.

And I agree. But I also agree there is no morality to a polar bear eating your face. That’s just nature. There are lines, I don’t know your specific context.

For me, I was raised removing tumbleweeds. One of the most tenacious and invasive weeds out there. I don’t even think they are native to my country. But I sure hold no remorse pulling them up the same way I would a dandelion (even if me blowing on one is technically spreading it out).

If I was standing there with a gun to your head because I’ve decided you’re offensive to my garden you wouldn’t genuinely believe it’s fine for me to kill you simply because you can’t do anything to stop it.

Sure. Then a man with a bigger gun will at best arrest you and you’d be thrown in jail. We realized human on human violence needs to be regulated to make it as close to zero as possible. The police have a monopoly on unchecked violence, so our options without consequences are limited and discouraged.

There’s a clear and obvious distinction between taking another life as a necessity because you need to eat in order to survive, and killing on a whim because you decide you don’t like how one form of life looks.

Yup.

I’d certainly pay money to watch a bear chasing you down and eating you so that I could witness how much you’re definitely not talking out your ass when saying that you wouldn’t complain about it, because bears needs food.

I’d run. I’d try to defend myself. I’d do my best to preserve my life. But trying to shame a bear seems like a useless endeavor. Thtat’s all I’m trying to get across with my metaphor.