You're right that this example throws a wrench in my genetic relatedness argument. Stepping back from that, the deeper question is: how obvious is it that a creature can suffer similar to my own suffering? If it's obvious, it's obviously a bad choice for domination and consumption in my book. Plants do not have this outward obvious ability to suffer imo.
Like, what if some "thing" has very complex behaviours as per your existing items, but their external signalling rate is so slow that it takes hours for them to start displaying their reactions?
(note - that's just an exaggerated thing to convey the idea)
This is ideological BS, not scientific facts. Many of this kind of posts are just pseudoscience in its most pure form.
An animal is obviously more related with another member of the same kingdom than with another member of a different kingdom. Why? Because taxonomy works exactly like that.
If you find a single animal with DNA more closely related with a plant that with another animal that would destroy the entire classification of life.
Molluscs can have, and do have, chloroplasts under its skin. We know about several species of molluscs that have it, but this is borrowed stuff. To a naive person could appear as one single species in a genetic analysis, but is an artifact. We know not to trust blindly in those analysis
I have read that cephalopods are on a genetic tree that diverged from our own before the emergence of photosynthesis. It seems that we are more closely related to most plants that we are to octopuses... yet they are able to befriend humans, clearly have emotions and undoubtedly experience pain. It is even the case that they generate hormones that are nearly chemically identical to our own for similar emotional states, fight-or-flight for example.
So, octopuses are pretty similar to us and yet more distant genetic relatives than your salad!