Non-interactive either-can-spend transactions

In Bitcoin, Bob can post an address, and Alice can send to it without any interaction with Bob.

In Grin, Bob can post a slate S, Alice can interact with it, but Bob must finalize S before it hits the blockchain.

Is it possible for Bob to initially post additional information with S, so that Alice can finalize into an either-can-spend output without further assistance from Bob? Then, when Bob comes online at a later date, he can “claim” the payment by spending from it into an output he controls.

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Alice could just hand Bob the blinding factor to one of her UTXOs.

The problem with an either-can-spend UTXO is that Bob needs to come online and actually spend it in order to ensure that Alice won’t spend it. I can’t think of a situation where this would be useful. If Bob trusts Alice enough to do this, why can he not simply trust that Alice will pay at a later date (i.e. when the slate finally has been responded to and finalized)?

Correct me if I’m wrong, but the scenario I described, Alice never needs to send information to Bob. It is one-way information flow: Bob -> Alice -> Blockchain, then later, Bob -> Blockchain.

I see. Good point. Do you have a scenario in mind where this would be useful?

I’m still brainstorming, and opening up the conversation to find out if it’s possible.