That's an excellent question, and here's how I'm going to answer it: let's keep our eye on the harm ball here. If there's not harm, then okay.
In fact, one man's poison may not be another man's. Smallmouth bass in different parts of Canada are a good example of this. In some parts of Canada where smallmouth bass are indigenous, are native, people love to have them in their lakes. They love to catch them. They love to eat them. In other parts of the country, northern Ontario for example, where smallmouth bass are not native, the bass have detrimentally affected some of our cold-water trout fisheries.
So I say let's use the harms test. If there's not harm, then let's keep our eye on the ball. There is a spectrum here, whether we're talking aquatics or terrestrial. Not all non-indigenous species are harmful to ecosystems, people, or society, but some are catastrophically harmful.