If we lose those frogs, it most likely would cause a cascade across other species. There are lots of things that eat frogs.
They're only applied to thing we don't want to do.
In reality, it's always true that we don't fully know, so applying the argument always means "let's not do this".
In the end, whose lives do you prioritize given the lack of information today, and the lives at risk today? Deciding to do nothing still costs lives, and potentially drives us further into the bad state area.