Let us know how it goes!
If procuring cause is in place or BRA signed, negotiate a deal.
Don't trust this buyer to suddenly be loyal to you.
It just doesn't seem to be their nature or perhaps you poached a client.
We just don't know.
However, if that agent finds out that the buyer put in offer with you (and it was accepted), they can come back and try to get a portion of the commission from your (new) agent.
It's called Procuring Cause, check it out.
This is also an ethical issue, and one that ends up filling the court called "procuring cause". It's not worth it, return the client to the rightful Agent!!