1. Sure they could
2. I imagine you'd have lots of situations where the probability of concurring, even with truthful responses, would be close to zero, so this wouldn't be a useful metric. Questions like "name some exotic birds that are edible, but not commonly eaten" could have thousands of valid answers, and so we wouldn't expect truthful responses to concur. Even for simpler questions, concurrence likely won't be verbatim, so how to you calculate whether or not responses have concurred? You need to train another model for that presumably, and that model will have some nonzero error rate, etc., etc.

I'm incredibly interested in this sort of stuff, but have never seen this article before, so thank you for sharing:)

I feel like the implicit claim in your argument is that "if we end up considering fractals, crystals and rivers intelligent, that's bad." I don't see why we should accept this claim necessarily. What's wrong with biting that bullet? Does the inverse -- believing that there's a particular "type" of complexity that's special, and uniquely human/animal focused, that isn't present in any other part of the universe -- really hold any important value, or is it just born of a sort of emotional attachment to anthropocentrism? I'm inclined to believe the latter.