Well, it seems like the part of this conversation that had to do with the original claim and counterclaim has petered out. Do you agree with this claim:

In a truly deterministic universe, the concept of "faster-than light interaction" is largely nonsensical.

If so, then we can keep going. If not, then we can move on to discuss the nature of possibility and its use against claims like the above. If you are still interested enough in continuing, that is. I won't detain you against your will.

...

Making testable predictions about empirical reality? That's a pretty high bar. For example, counterfactuals do not fare well under such rules.

Is it? I'm happy to lower the bar; I didn't think this definition through very much. But thus far I see no reason to revise it. Why don't counterfactuals fare well? Are you saying that under my definition of possibility, counterfactuals are impossible? That would mean that we shouldn't consider theories that involve counterfactuals, which seems to me to be false, though it might depend on what theory of counterfactuals we are using.