Is it a violation, an illegal screen, or nothing?

[Kelvin green]

Coming on the floor is to prevent deception plays or to prvent the offense from keeping a sleeper outside.

I would read this that once you are authorized to be OOB you have to go directly back in bounds.

You would not let the OOB player wait so he could go staright in. He cant stand there for 30 seconds to go to the nearest spot.

I belive this is a more of a time thing than a straight line. If the player runs down the OOB line it took to long to get it...

This is a common sense play that is pretty obvious when a player is gaining n advantage