It doesn't seem like you're rebutting their actual argument to me... They're not talking about the movie in a general sense, they're referring to its effects on writing.
Your first point doesn't appear to me to relate to the quote. It doesn't say you're making up stuff, just that there's little info. Second point is kinda odd sounding to me. They're talking about the movie's effect on fan fiction.
Part of writing is the great opportunity to make the imagery of a story out of nothing, and use your vision of an area or character in it. It's all completely your own, in particular, when you're writing about topics with very little info, or that have never been solidly formed in a video/picture. Once something exists in a physically visible sense, you can't really write about it when whatever you came up with is so much different.
Sort of a larger version of going to watch a movie based on a book you read, and everything looking nothing like you thought it would.
As for your third point, it looks more like just some catchy slogan-ish thing to end a statement with. Though the person in question might consider the Multiverse bad, I don't know. Certainly a harsh generalization though, which seems to work against the rest of the quote. I agree with you there.
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I don't pretend to talk on behalf of whoever wrote that. I don't even know who said person is. That's just my take on it.
Personally, I think this movie is an interesting concept. If it gets pulled off, it'll likely be really awesome. It'll take a whole lot of work though...
EDIT: Wow... that came out bigger than I expected. O.o