To be clear, I am not playing with language. By packing I mean adding more jurists to the court.
So to simply use your reasoning: If the Dems had the power to ADD SEATS, would I expect them to do it? Why is that even a question? They would be stupid not to.
I'm simply making the point that the "do whatever you have the power to do" reasoning can apply to anything. So, if one does it here, then there can be no complaint when another does it there.
The representatives are supposed to act in the best interest of the nation. Not in their own interests - even if there is no law preventing them from acting in their own interests. We should not elect representatives who do so, even if we might like the acts they commit, because they will only result in those acts wilfully being committed against us in the long run.