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.
No. While both Roe and Obergfell roughly claim backing by the 14th amendment and its due process clause, Roe and Roe alone had to reach for the invented “right to privacy” to justify the application of 14th amendment protections. Alito makes that clear.