It matters how they react to stimuli because we do not know, and
can not know, whether they have consciousness or not, and so the safer assumption is to treat them as if they do.
But if we accept that we also need to consider that we do not know, and can not know whether other entities are conscious or not either.
We can only tell whether they present as if they are.
And we should consider that when deciding how to treat them.
Furthermore we should be cautious about how high we set the bar.