Problem with that then becomes it removes the origin of Obsidian from existence. So the bathed in time absorbed by Ian Karkull has to occur for him to exist.
Since it has to be for Alan's son to have his powers it makes zero sense to not also have the effect it had on the team's life expectancies and vitality.
The case for Sylvester and Pat always was a time displacement after the seven soldiers battle with Nebula man. The JSA saved them from the times they were thrown to and brought them back to the present. The only one it didnt keep young was Vigilante who they found 20 something years after he'd been sent to thenold west