I'd have thought that the purpose of the quote about the trees is a way of pointing out that, in this respect, the Israeli forces have done something that even Deuteronomy didn't advocate. I'd assume that anyone familiar with the history/mythology of the conquest of the Holy Land would have been aware of the genocide described in this part of Deuteronomy. I'd also assume that the website is directed primarily at people who could be expected to be familiar with such things.

The quote is surely an expression of a kind of bitter humour, rather than a distortion. It reminds readers of that aspect of history, but without pushing it to the centre of the stage. Using the full quote in that context would merely have been inviting people to argue about what happened thousands of years ago rather than what is happening today. (And it's having that effect here.)