What you are saying doesn't go against that it should be a goal line drop out, give my you are talking about an attacking player making the ball dead by touching it with a foot in touch. The ball has to touch the ground to be considered dead. If a player is standing out and punches the ball he is considers to have made the ball dead and possession is given to the opposition.
If you need the rule though, there is a specific mention of the exact situation from last night in the rule book:
"SECTION 9 - TOUCH AND TOUCH IN-GOAL
Dead Ball Line Restarts:
Should a kick be made dead by a defending player straddling the dead ball line or touch in-goal line, play will restart with a goal line drop-out."
You're reading the rule wrong. The drop out applies when you have one foot in play and one out of play. When both feet are out, which they were last night, you can't be straddling the dead ball line and it is a 20m tap