God advice there. It's also not a bad idea to carry a money clip with a twenty on the outside, and ones inside. In an iffy situation, toss that money clip, then get moving.
we don't need any more stinking ways to "get out" of actually fighting someone...
I would do it differently.
Have two one dollar bills easily reachable in your pocket.
Offer it to them, but with your arm not extended at all, with your hand hardly in front of your hip, so that they have to step in near you to take it.
Kick them in the knee when they do.
If there is any crowd there, they will immediately become spectators when they see the ‘robber’ writhing on the ground.