that could be a good idea to prevent people losing nxt.
like the sender can put in a timelimit for the buyer to accept and if he doens't the transaction is not executed.
Kinda like in any online game that requires a group. You have to get verification for groups and such, Someone sends an invite -> other person accepts the invite. If the other person doesn't accept then the invite is cancelled.
Would definitely help with accounts of no owners. Add that to the two step verification. Click to "Send" -> (Gives you a review your order page) Click "Confirm to Send". So at least they can get verification of who/how much being sent to whom.