Yes and no.
They can't benefit from having been a lazy runner, but neither do they remain lazy runners for the rest of the game.
At some point they are either put onside, or we go back to open play.
It would obviously have been better if COS had provided examples. I can't believe the referee never once penalised 'material' lazy runners as was suggested.
[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.
11.9 LOITERING
A player who remains in an offside position is loitering. A loiterer who prevents the opposing
team from playing the ball as they wish is taking part in the game, and is penalised. The
referee makes sure that the loiterer does not benefit from being put onside by the opposing
team’s action.
Sanction
enalty kick at the offending player’s offside line[/LAWS]