Something like:

Alice sends a request to Bob, "hi Bob, can you look after a secret share for me?" Bob replies "yes, encrypt it to this ephemeral public key bob_e". Bob's stores this key on disk, for now. Alice also generates an ephemeral key, alice_e and encrypts the share, sending bob alice_e.public, secretbox(share_bob, alice_e*bob_e) then deletes alice_e's private key. (note: alice sends the public key she used to bob, he'll need that to decrypt the share)

I think I see the intention of this, but I've got tangled on which keys are being used where.
I'm assuming all keys are assymetric, so there's alice_e.public and alice_e.private.

Re-writing the story with more detail it might then look like :

1. Alice ask Bob, "hi Bob, can you look after a secret share for me?"
2. Bob replies "yes, encrypt it to this ephemeral public key bob_e.public". Bob's stores bob_e.public and bob_e.private keys on disk, for now.
3. Alice also generates an ephemeral key-pair, alice_e.public, alice_e.private and then sends Bob:
   • secretbox(share_for_bob, alice_e.public*bob_e.public) (encrypted share)
   • alice_e.public (he'll need that to decrypt the share)
4. Alice then deletes her ephemeral alice_e.private

Things I don't understand:

• I can see where alice_e.private is ever used
• aren't all of the keys that were used to make the secretbox key (alice_e.public*bob_e.public) now on the log? .. making it not the ephemeral