The point dear chaps is that if they are in an offside possition as the ruck ends, just because the offside lines disappear it doesnt put them onside! Whilst bound in they are fine but IMO if they were bound to the side of the ruck (infront of the back foot) and advanced and tackled the SH as the ball leaves the ruck I would call them offside.... (light blue touch paper and wait}
Then you would be wrong in Law.
Forget the earlier talk about offside in general play. Its true, but irrelevant to this discussion. We are only talking about
Ruck Offside - Law 16.5 - and only about those players who are members of the side not in possession when the ruck ends.
Such a player bound into the ruck cannot be offside at the ruck even though he might be technically ahead of the hindmost foot. He is not entitled to grab the SH and pull him into the ruck before the ruck ends, however, once it does end, he is entitled to immediately take part in play. If he is on his feet and he can tackle the ball carrier, slap the ball out of the ball carrier's hands (provided it doesn't go forward) and do all the other things that an onside player can do.
A player is offside at the ruck when they are
not a participant in the ruck, and are ahead of the hindmost foot. This can happen when they are simply standing beside the ruck not bound to it (offside pillar), still retiring when the ruck ends (lazy runner) or if they detach before the ruck ends. In all cases, those players remain offside even after the ruck ends. They cannot take part in play at all until they are made onside...
[LAWS]
11.8 PUTTING ONSIDE A PLAYER RETIRING DURING A RUCK, MAUL, SCRUM OR LINEOUT
When a ruck, maul, scrum or lineout forms, a player who is offside and is retiring as required by Law remains offside even when the opposing team wins possession and the ruck, maul, scrum or lineout has ended. The player is put onside by retiring behind the applicable offside line.
No other action of the offside player and no action of that player’s team mates can put the offside player onside.
If the player remains offside the player can be put onside only by the action of the opposing team. There are two such actions:
Opponent runs 5 metres with ball. When an opponent carrying the ball has run 5 metres, the offside player is put onside. An offside player is not put onside when an opponent passes the ball. Even if the opponents pass the ball several times, their action does not put the offside player onside.
Opponent kicks. When an opponent kicks the ball, the offside player is put onside.[/LAWS]