I agree that motive is likely in at least one justice. But at the same time, if they really wanted to get back to original principles, they would have to take a wrecking ball to virtually every agency without being able to provide any substitute for the load bearing bits. I think these artificially narrow rulings are what some of the justices think is the middle ground to work in that direction without bringing the roof down. Thomas in particular has advocated for simply taking out the walls and trusting congress and the states will somehow fix everything and it isn't their problem. I think his opinions have occasionally been horribly flawed, but I see his vision and get what he is hoping for. I suspect something like that is the only way a representative democracy could recur in the US. Right now, states with strong geographic bents towards authoritarianism can use power of the federal executive to strengthen their position. If the federal executive had no agencies and was powerless the way Thomas suggests, those states wouldn't have much impact. But that entails acknowledging the entirety of the federal bureaucracy is unconstitutional and creating all sorts of power vacuums. Who knows how that would turn out? I increasingly think it couldn't be worse than the likely end state of a federal autocracy if we don't.