I think the lefty justices granted certiorari because they had nothing to lose by taking it.
Also this case is unusual in that BOTH sides of the issue wanted the USSC to hear it. I’m not sure why the pro-2nd side wanted it heard, but it suggests confidence that a wider, favorable ruling could be obtained.
See my post 89. The issue to be reviewed is VERY narrow, not wide. The Court will only decide the collective/individual issue regarding guns for use in the home in Washington DC.
BTW, how do you know that both sides wanted it? I haven't been able to find any tally of votes for certiorari on this one.