I think it's bimodal. Either Twitter is worth like 100$+ per month if you're a journalist/brand, or it's less than 0, and in Stephen King's case he's correct that Twitter should probably be paying him.
It would be fun to try and mediate the discussions to try and convince which of the big ego'd celebrities/journalists/politicians are of value to twitter and twitter should pay, vs which are a sink and they should pay twitter. Hey monetezation plan! I would pay good money to watch that reality TV show.