Mm, no I think what this shows that in just the same way as the future is uncertain (you don’t know which path you will observe an electron to take), the past i

Mm, no I think what this shows that in just the same way as the future is uncertain (you don’t know which path you will observe an electron to take), the past is uncertain in the same way (you can’t know which path an electron took). They’ve just expanded that principle to a cosmic size (there are several past histories, diverging on the Planck scale, that lead to the same present day observations). That doesn’t mean physics is not reversible, it just means there isn’t a unique way to reverse it. Which, we already knew.