Regarding ripeness, I think they wait until until a case has been adjudicated before accepting it. Here, it seems the question has been procedural vice substantive. Agree the arguments will be interesting especially linking the killings specifically to Remington vice any other manufacturer.Speaking to your thoughts about Thomas and Kav. wanting to solidify Heller, I wouldn't be surprised if that's the case. I wonder if this case, as you said isn't as "ripe" as they would like the case to be. Although, some ripe cases are still ruled on by SCOTUS very narrowly.
Even though SCof CT. voted that Rem. can be sued I think Cox has an uphill battle even in a more liberal sided court.
I believe the 2nd amendment was trying prohibit exactly what CT is trying to do: allow a government to have a class of weapons out of reach of a citizen.