I have a hard time believing the BBC can't 'sack' Moffat (or move him to just Sherlock
) if they truly feel he's endangering the show. This ain't 1984 anymore, Doctor Who
's a national treasure at this point.
As for Hurt's character being some kind of personal "FU" to Eccleston, bear in mind Moffat claims he's had a plan for "The Fields of Trenzalore/the Fall of the Eleventh" for years now. If the latest post from whistleblower is to be believed,
Which was shot months before the special. Which means his character was created and written well before Eccleston decided whether he was gonna be in the special or not.
Now if that's the case, it truly doesn't matter whether Eccleston's in or out where that particular character is concerned, and I'm sure Moffat wrote the script with that in mind.