I’d be curious to know why it would be wrong for Christie to appoint a Republican. He’s entitled to appoint whomever he chooses, and from what I’ve read of state statute as posted elsewhere, he is under no legal requirement to choose a replacement from the same political party as the deceased.
It’s his choice. If the voters disagree with that choice, they have appropriate recourse through the ballot box.
Because the people elected a Democrat.
I'm not talking legal requirements. I'm talking fairness to the voters.