I think it's fairly likely that Cal here was recruited in to the Mafia and that's why he suddenly became demotivated.
For the newer players, you need to ask yourselves whom this arrangement favours. Remember, if I were scum, I'd be able to nominate whomever I please. I'd have a much better chance at getting a player like Joseung lynched over Cal. Yet here we are, my vs Cal. There is very little chance of me winning that, I know it, everyone knows it. Thus it would be very suboptimal for me as Scum to do it.
I doubt that's going to sway anyone. But it doesn't matter, because I'm going to flip town, and then you're going to have to lynch Cal. After that there should be 2-3 scum left.