Roberts went right for the standing issue. If standing falls by the wayside what is the effect on the lower courts rulings?
If your state won’t defend the results of a public vote who can?
If they deny standing, they can deny it for only SCOTUS or for all federal courts. The former means that the 9th Circuit ruling stands (gay marriage allowed.) The latter means that the CA Supreme Court ruling stands (gay marriage banned.)
In California, when the attorney general will not enforce a law, the proponents who brought the initiative to the ballot can legally defend it in court, which is why the CA courts rightly granted standing.
Read the portion of the transcript where Justice Breyer addresses public actions. It's close to the beginning of oral arguments - like 3-4 pages in. The link is in a previous ping I sent you today.