Both people are using the same formula. For somebody who usually has to bum five bucks, I just won the lotto.
To be swept off your feet is to succomb to a dynamic courtship. Somebody romances you, and their campaign is super effective. They win your affection. You fall hopelessly (helplessly) in love.
Okay, she's usually immune to all that. It doesn't usually happen to her.
But this time it not only happens, but she gets it twice as strong - a double dose.
What's stronger then getting swept off your feet??
Getting completely blown away.
I don't think "blowin' in the wind" is chosen because of the image in the song, but because it sounds clever, and fits the swept away thing. It trumps "swept off my feet."
So the guy answers back in kind. His idea of romance was a quick free-fall. And he always made sure it was a short one. (The ripcord opens your parachute and stops your free-fall, as you suggest.)
What's even more thrilling than a short free-fall?
Soaring like a bird, endlessly.