The letter starts:
Shavuos honors the receiving of the Torah, the time when Jews accepted the responsibility to be a light unto the world. Part of that responsibility is to accept God’s creations. Koheles Rabbah (VII, 13) states, “See my works, how beautiful and praiseworthy they are; and I created all of it for you. Be careful not to spoil or destroy my world because if you spoil it, there will be no one after you to repair it.”The quote appears to be talking to all of man, and telling him to take care of the world and not ruin the environment, for if you spoil it, it cannot be undone.
In fact, the full quote is:
Thus, it was directed to Adam haRishon, not to all people. The beautiful and wonderous works were the trees of Gan Eden. The ruining of it was not by chopping down trees or polluting a river but rather by sinning by eating from the tree of Knowledge of Good and Evil. And the quote would have made that clear since it continues from "there will be no one after you to repair it" with "and not only that, but you will cause death to that righteous person" (who is Moshe, as we continue to read). Thus, the topic is refraining from sin rather than environmental protection.
And as we see, he did mess up and caused all this.
Perhaps one can extrapolate from all this an environmental message (and perhaps not), but this is either deliberately or accidentally dishonest. And where you start manufacturing quotes by taking them out of context, I begin to wonder whether any of the sources legitimately bolster your claim. (In fact, this has been true in the past for other environmentalism devar Torah claims.)
Indeed, his other two quotes make use of ellipses, which make me wonder whether he is Dowdifying the quotes. I don't have time right now to examine them, though.