An interesting and valid point.

The issue of directorial authorship on these sorts of occasions is a hoary old question that rears its head on a regular basis. For example, how much of The Adventures of Robin Hood (1938) was directed by Michael Curtiz, and how much by William Keighley? I'd say Curtiz's vision prevailed, but it's impossible to know for sure.

There are also scenes in The Lord of the Rings trilogy (2001-3) which were directed by Fran Walsh rather than Peter Jackson, as is made clear in the documentaries. He did the bulk of it, but with the various pressures and challenges they faced, simply couldn't be everywhere at once.

There was also a big question mark over how much Tobe Hooper directed Poltergeist (1982), and how much of it was really Steven Spielberg (whose sensibilities are inherent in the film throughout, though he is credited as producer rather than director).

I daresay like the above, we'll never know for sure in this case either. But I still liked the film, despite my reservations. :)