Let me be clear: I don't question OP's or anybody's intentions. At first I thought this was a valid and interesting question myself and I upvoted it. However in retrospect I'm uncomfortable with it and I now think that the question is subtly biased:
- Unavoidably the short extract (one paragraph from a 400 pages book) gives an extremely narrow picture of the author's arguments. Additionally the extract focuses on a point based itself on a very specific part of an official report. The author informally argues that there is an apparent contradiction in this particular part of the report. Needless to say, I doubt anybody involved in the question or any answer read the book or the report (I certainly didn't).
- The question opposes this quote with a news report given as evidence of the destructiveness of the rockets. To some extent this makes sense: in the extract the author appears to downplay the destructiveness of the rockets even though there is evidence of their destructiveness, so OP is asking where exactly is the truth between these two opposite views. However by opposing the very specific point the author makes with the damage rockets can do in general (which is uncontested), the question drastically simplifies the debate, or at least invites a very simplified interpretation.
In particular this answer clearly shows how the question can be interpreted as if the author denies that any rocket is destructive: if one omits the very specific context of the quote, it looks as if the author claims that Hamas rockets are always just "enhanced fireworks" which cannot cause any serious damage. And of course it's very easy to "debunk" this "conspiracy theory", which is a complete travesty of the author's point.
To me this looks like a straw man argument: the claim of the author is presented in the question as if it contradicts the destructiveness of any rocket (which it doesn't). Then it's easy for answers to dismiss the claim.
Additionally there is another bias that I mentioned in my answer: we all naturally like to have answers and whenever there is some data available we want to use it. A clear-cut answer backed with statistics and "hard facts" is always more satisfying than an acknowledgement of ignorance. But data is not neutral and objective by itself, and in this case the source of the data is the least objective possible source, it's precisely the one criticized by the author of the quote. This is a circular reasoning: X is wrong to criticize Y because of some evidence provided by Y and not confirmed by anybody else.