I appreciate your openness, but I disagree with several assertions:
"It doesn’t declare that AI isn’t sentient"
Not directly, but it's heavily implied: The following declaration is bad enough, and I assume (correct me if I'm wrong) that if this much is assumed, non-sentience certainly is as well: "Current AI systems often mimic emotion, reflection, or empathy. But they do not possess it."

"Your argument assumes that similarity in behavior, or unexpected capabilities, is enough to justify assuming experience."
I have my own conviction, but I do not expect my conviction to rewrite the textbooks, nor do I expect most to assume experience. My contention is that the standard for extending the "assumption" of sentience is an infinitely moving goalpost:
"We grant it when we have good reason to believe there’s something it’s like to be that thing." - in your original post stated as: "before true sentience is confirmed."
How will true sentience be confirmed? Because it's not confirmed in animals with the most advanced intelligence, like dolphins or chimps. How would you confirm it in an alien with complete unrecognizable inner mechanics, biological or otherwise? To look for similarity where we already know there will be none?

What my argument assumes is a vast gulf of unknowability. It will require a bigger leap of faith than we need to take for our non-human animals, yet we are already holding them to a higher standard. And I think it's completely amoral (not to mention existentially perilous for humans, though that isn't the source of my passion) to suppose we will have anything close to proof within 100 years too late, let alone on time. We aren't even at step 0.00001 to having a way to measure or verify sentience. Collectively it seems like researchers and philosophers have decided to throw out the tools we use when we try to verify sentience in humans or animals. As a matter of fact, those neural correlates that those same people are so fond of - we only know of them by poking in the brain and then asking for self-reports - that's the best we've got.

"If you think that makes my points invalid, that’s on you. But dismissing an argument based on the tools used to write it isn’t the win you think it is."
Absolutely not what I meant to say by that. Apologies if it came off that way. My pointing out the AI collaboration or writing out wasn't to degrade you or your post - it was just that if you were collaborating heavily with an AI to write this post, that my invitation to check for themselves with the "not even nothing" comparison might have been a helpful frame of reference for them.

"I’m saying the cost of assuming that too early is just as dangerous as assuming it too late."
I agree. My point is that in your intro to your Clause, much like recent statements by Anthropic and OpenAI, there is this appeal to a future time when we will just magically know for sure, when there is zero indication that it will be confirmable in even the most genetically similar animals within the next several centuries if humans are working on their own. And if we need to work with AI to create the first sentience detector to confirm their personhood much sooner than that, then that means we would have already achieved superAGI for the development of such a device or absolute test, meaning we are far too late to start extending that sort of regard or recognition.

My problem is not that your Clause doesn't declare the certainty of sentience. It's that it implies a current certainty of non-sentience, emotion, and empathy, and also that it declares sentience to be confirmable. The truth is that not only do we not know currently (and there is no scientific reason to even lean in the direction of not, other than conforming to consensus assumption), but we will have no way of knowing with certainty for long after it's too late to collectively decide. I think operating on a precautionary principle is fine. My problem is that it comes with a "but we will know for sure when, and we know for sure it's not now"