Wtf are you retarded? Twitch sub is 5$. Nobody pays frickin 5$ to clear heroic Nighthold. They are free to choose who they want to invite to their raid group, if they want to give prio to their subs from twitch they are allowed too. You either are sub or you are not, nobody is selling raid spots for subs.
It's like sb said "prio for Hunting Club members" and you would freak out its selling raid spots because before while applying to Hunting Club you need to play 5$.