A lot of people are curious about this, so a former Sinclair journalist sent me a Sinclair contract. Here are the parts about quitting/getting fired. (See that clause about politics? It forbids employees from expressing their personal political views, but not their employer's.) 
Also this is sort of unrelated to the whole fake news thing, but this bit also caught my eye.
Oh boy. If there's a lawsuit/arbitration, Sinclair is guaranteed attorney's fees if they win, but the employee isn't guaranteed attorney's fees if the employee wins.
This part really jumps out at me: This Sinclair contract says the TV station can fire this journalist if they become disabled and can't "present a pleasant personal appearance and a strong, agreeable voice”
