First part - referees allowed players to keep hands on the ball during the tackle way before the ELVs were thought of.
Interpretation is the wrong word but is shorter than saying. "A convention used by referees especially during the professional era wherein referees ignored the law as it was written because they thought the game would be better for it - or because they copied the big name referees on TV and if the ref stars did it, by golly they would too."
By allowing players to tackle opponents and close a blind eye to them not releasing and allowing them to swing themselves up still holding on, referees stuffed up the game. It is why we are having a hoo-haa this year trying to reverse the bad habits of old referees who thought they were doing wonderful things.
The change is not an "interpretation" öf the law it is observance of it.
Second part - "even after the maul had formed." I assume you meant to type "ruck" instead of "maul."
In May 2009 there was a ruling subsequent to a request to the IRB because the handling in the ruck law was unclear. It had nothing to do with the ELVs either.
The ruling, in effect, said that players who got their hands on the pill at the tackle by legal means could keep them on after the ruck had formed. In other words they could keep trying to tug the ball out so long as they were still legal - not going to ground or resting body weight on other players, which is the same thing. There could be one player, or one from each team, or theoretically more. No player who arrived after the ruck formed was allowed to do this even if a team mate was.
This ruling is still in effect but note that this has nothing to do with the first part. They are two separate things.
If the person with his his hands in the tackle was the tackler, and not just somebody arriving, he must still release the tackled player as the first item in the tackle transaction. Then he should get to his feet without using the tackled player to get himself up. Then he can fetch the ball provided a ruck hasn't formed yet. Then he can keep going after it has.
By then he should have been taken out.
Thus - neither had anything to do with the ELVs.