The definition privileges action, which is why vegan philosophy is generally fine with stuff like foxes hunting birds but not humans hunting foxes to save birds.

Taking action to depress ants to save others would go against the ethos as defined:

“Veganism is a philosophy and way of living which seeks to exclude—as far as is possible and practicable—all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose; and by extension, promotes the development and use of animal-free alternatives for the benefit of animals, humans and the environment. In dietary terms it denotes the practice of dispensing with all products derived wholly or partly from animals.”