This is something that would have been laid down in their original contract when they had no idea what they were going to do or how the movies would be received. Would hardly call it butthurt. Though 1 billion does seem like a bit of a stretch. To date, the only non-Avengers movies (including Civil War in this) that broke 1 billion are Iron Man 3, Black Panther and Captain Marvel I think?
Seems weird this would pop up out of nowhere when this deal has been such a super secret to this point though. Can't help but wonder if it isn't possibly a BS marketing ploy to try and up the numbers while they can. Probably on Sony's side since box office money goes to them. It also seems just like them to hold an IP hostage. >_>