Spot on. It isn't manipulation. He's the one who has to stick his neck out so to speak
The first thing that popped into my mind when I was reading his post was along the lines of
Her: telling the edible hand cuff anecdote
Me: "Are you threatening me? Is that some kind of threat? I'm not sure I could trust you if I were tied up and helpless. What exactly are you planning on doing to me" Treat the whole thing as a joke and be flirty.
Then to ask her out I would do this long drawn out "It's cool talking to you. If only there were some way two people who worked together could sit down, grab a cup of coffee, and talk outside of work. I can't believe no one has ever invented some kind of casual ritual where two people could meet outside of work. You would think in all the thousands of years of human development someone could have come up with a way..............."
And just keep going until she suggests it herself
If she isn't too bright though, that could take a while