Exactly what Joss Whedon is doing as the emergency holographic director on Justice League has been a major topic of speculation.
At the same time, the simple fact that Joss Whedon isn’t Zack Snyder also can’t be ignored.
There’s only so much that can be done with the limited time and money allotted to the reshoots.
As much as Whedon might be trying to simply fine tune Snyder’s movie, he can’t read the man’s mind, and so some of Whedon’s own style and perspective are going to become part of the finished product.