You are right didds. I was going to tell the story about a YC four years ago which lasted 20 mins and 17 seconds. This arose because eleven minutes had gone but the referee refused to let the YC back on (non-offending) at a penalty and insisted waiting until the lineout. They missed touch and a combination of continuous play and other penalties led to the 20 mins+. He was only allowed back on when a scrum was opted for. Even then the opposition objected!
yes - you need to balance the non-offending team's right to go quickly, with the YC player's right to come back on.
scenario
- blue have a player in the bin, 11 mins gone
- you award PK to Red
- there is a pause while red collect the ball / confer about what to do. ie they have NOT tapped and gone
- the blue YC player is standing on the the touchline
- you can just wave him on to the field. Why not? he's done his time.
Red have the right to tap and go, but if they don't do that, I don't think red have the right to keep him off the field....