This is a variant of appeal to perfection, which itself is a type of false dichotomy. The general form of a false dichotomy is a forced choice between only two options, "it's either A or B," when it could in fact be C. In this specific variant the choice presented is between a perfect solution or giving up entirely.

The way to defend against a false dichotomy is to identify the plausible third option, and in the case of the appeal to perfection, that option is to improve on the default, even without reaching perfection.

In the case given, the "perfect" solution kills no animals, the "pretty good" solution kills fewer (than the default solution, to continue as is).

This is a variant of appeal to perfection, which itself is a type of false dichotomy. The general form of a false dichotomy is a forced choice between only two options, "it's either A or B," when it could in fact be C. In this specific variant the choice presented is between a perfect solution or giving up entirely.

The way to defend against a false dichotomy is to identify the plausible third option, and in the case of the appeal to perfection, that option is to improve on the default, even without reaching perfection.

In the case given, the impossible "perfect" solution A kills no animals, but the "pretty good" solution C kills fewer than the default solution B (to continue as is).