Yes, I know he didn't pitch the original idea.. but the Moment he was made director, he can, if he chooses try to get any part of any script re-written... if it doesn't jive with him...
Just like an Architect wouldn't just draw a building anyway their owners want.. they'll have to make sure it won't collapse...
The buck always stop at the director.. that's what DIRECTOR means.. he's the GUY in charge... if he's not, then he's got no business being a director... he'll just be a 'yes man'... the best directors will have scripts re-written, and re-written until their are satisfied...