9 people with most of them in their 50's and 60's. That's a lot of experience in law. Most of them also have impressive backgrounds.
That could be said of people like Earl Warren, Sonia Sotomayor, Ruth Bader Ginsburg, Stephen Rheinhardt, and lots of other really rotten judges. The problem isn't a lack of competence. It's a lack of character, discipline, and courage and a overwhelming presence of power-hunger.
What you think of Luther's case is fine. People can agree to disagree on that. But you shouldn't be deferential to the Texas Supreme Court just because of who they are. They're no different from any other group of political hacks, and they're more than willing to butcher the constitution and laws to force their preferred outcome in a given case.