Sure, if visible/invisible is the key attribute for H2, then H2 makes the same predictions as H1. In the absence of any clear claim about what attributes matter to H2, I'm not sure H2 is coherent enough to test.

Anyway, IIRC the experimental protocol EY referred to involved asking people how much they would grieve over the death of an N-day-old human for various Ns.

"Extending the curve" for that protocol into the pregnancy period is easy: ask people how much they would grieve over the death of an N-day-old fetus for various Ns. Beats me whether this tells us anything that matters, but I have the same problem with the original experiment.

I also admit to not really understanding what the curve of "reproductive potential in the ancestral environment" actually is... what are we measuring, here, and how are we measuring it? Perhaps if I understood that more clearly, it would be clearer how one could extend it into the gestation period.