We can come back later to WHY the charge is being made (that environmentalists are fascist) and to be honest, I wouldn't even try to anwser that without knowing more about the politics* of the person making the charge.

However the LOGIC is ridiculous

The form of theses arguments "proving" that the greens are fascist are ---
a) The greens are for X
b) The BNP (fascists) are for X
conclusion --- the Greens are fascist

Totally ignoring the differences in why (either) wants X or more important, whether X represents a "good" on it's own. Try a simple substitution....
a) YOU are in favor of washing your hands after using the toilet.
b) BNPs are in favor of washing their hands after using their toliet.
conclusion --- anybody who is in favor of washing his or her hands after using the toilet is fascist.

In order to use the "quacks like a duck" logic you need to be sure that "quacking" is a rare activity that only ducks are likley to do. Substitute "has feathers like a duck" or "swims like a duck" and the logic falls apart.

* To give an example (that I am rather certain does not apply in THIS case given the reference website). Many of you are probably familiar with factional fighting among the left splinter groups and some may know from history of times when they acused each other of being FASCIST (fascists were the main enemy of those days). WHY? The reasoning went like this. THEIR apporach (that of the acusing factiuon) was the only viable one or the best, most effective one, and by trying to organize toward other approaches the competing faction was resulting in a less effective fight against fascism, were sabotaging the one true effort, and so were effectively allied with the fascists/were fascists. Those of you who read this with disbelief -- read a little history.

Like I said, given the site to which were were referred, NOT the "why" in this case (although I have seen published attacks against "deep greens" rather similar in acusation (quacks like a duck logic) but for the reason I described.