I hate this excuse more than anything else in the world. It's his JOB to make it NOT look ridiculous.
Not true, never true, in this or any other reality. It is not a film maker's duty to take all aspects of the source material and make it work for film.
There are two main approaches to take when converting written source material for film: Strict adherence whenever possible OR do whatever the fuck your heart desires as long as the book inspired you.
And honestly, both methods work.
No Country for Old Men and
There Will Be Blood were the two best films of 2007 and, honestly, they are two of the best films I've ever seen.
No Country is incredibly close to the book.
Blood has nothing to do with Oil! other than the setting. The book is actually about a father and son working well together in a family business.
For a different example of how one technique working amazingly well while the other failed, compare Kubrick's The Shining to King's own remake for TV over a decade later.
Where Snyder fails, and where I'd venture to say, after having the opportunity to interview him, Snyder will ALWAYS fail, is in his deeper understanding of the source material's theme and purpose. While I agree he should have taken the squid out since it made me roll my eyes even in the comic book and modern audiences have been poisoned by Realism in their cinema, he failed to understand or convey the bitter/sweet compromise, the questions of whether or not to die for your principles. Sure, he had some of that in there ... but he put it in bot because he knew it was important, but because he put EVERYTHING in. Every character and setting is pulled straight from the comic with loving detail. He even shot the Black Freighter stuff and the two dudes at the magazine stand ... and yet he did things like change the movement of the characters and their fighting style, things essential to the theme of the book.
The book opens with Rorschach shooting his grappling hook up the side of The Comedian's apartment building, then having to slowly climb to the top, since he's older and tired, and climbing a building is DIFFICULT.
In Snyder's version, he glides to the top like Batman and perches on the ledge like Christopher Walked in The Prophecy.
We see the same thematic dichotomy later when Snyder shoots the "rebirth" fight scene with Nite Owl and Uber Slut in his badass, sexy slow motion ... when in the book it's this brutal, clumsy, painful experience that almost drops them with exhaustion.
Snyder's only hope with Superman is a script by Nolan's creative team. But even then, putting a nuanced script in the hands of a one-note director is not the best choice. The best we can hope for is that it's watchable.