The Constitutional references in the “gay” marriage decision did not rely on the penumbras and emanations dreamed up by the majority in the Roe decision. The “activists” who claim many other supreme court decisions could now be reversed based on the decision likely to overturn Roe have either not read Justice Alito’s decion or did not understand what Alito said. He made it clear (he very carefully weighed how to revoke Roe and Roe alone) how the reasoning revoking Roe does not extend to any other former SCOTUS decisions.
But even knowing that will not stop the fearmongers on the Left, as fear is always their fundraising and organizing calling card.
He made it clear he was dealing with Roe and Roe alone because Roe and Roe alone was the issue before the court. The same legal logic he utilizes in overturning Roe could be used to overturn Obergfell.