Actually, it was overturned in substance while being “upheld” in surface appearance. See above quote from the decision.
I disagree. The text itself leads to that interpretation, so they didn’t overturn it in substance either. Prop 8 really was about a word. Also, had prop 8 contained language limiting other rights, it’s clear that that would have also been upheld as that would not have altered the framework of the state constitution either.