Bartosz Milewski on Nostr: I read the introduction, but unfortunately it doesn't talk about the mechanism for ...

I read the introduction, but unfortunately it doesn't talk about the mechanism for the production of heavy elements. You're right that beta decay is slow, but I can imagine that the merger could produce neutron rich isotopes of, say, mercury, which would then slowly decay into gold. Either way, a neutron star has an abundance of neutrons. Even the outer crust contains neutron-heavy isotopes. It's the protons that are hard to come by.