You could put the bitcoin in a 1-of-2 multisig wallet, and give them one key. You keep the other key.
If they don't take possession of the bitcoin after some time or if they lose the key, you can take it back.
That's an interesting idea. Of course it only works in trust environment. But if they take it seriously it would be easy enough to take full control of the Bitcoin and move it to another wallet.
reply