I suspect that SCOTUS didn't see any reason to get involved in this mess. It's hard to decide what this case is about. Is it about prohibited persons? Is it about marijuana? Is it about state law federal law disconnect? Muddled cases often don't turn out well.
So now the Oregon medical marijuana user carrying a gun with a CHP might not get arrested by the cops or sheriff, tried in state court and sent to state prison; but he still get to be arrested by the FBI or DEA, tried in federal court and sent to federal prison.