Even if this is true (I have no idea, I'm not there) it is very hyperbolic. The only concrete thing they're saying is that one person has been threatened and assaulted. Not to condone such behavior in any way shape or form (or to assume that it happened or didn't happen), but comparing that to "ethnic cleansing" and the "massacres of Dafur, Sudan" is a bit of a stretch to say the least. And what's with this "list of suspected terrorists", they're trying to get people to inform on other rastafari people and say they are terrorists? On what grounds? By whose definition of terrorism? It seems quite suspicious to me. Anyone who had a personal beef with anyone could now inform on them and claim they are a "terrorist". As we know as soon as you're *accused* (not proven) to be a "terrorist" all your rights are thrown out of the window.
On the other hand, there are elements who at least *call* themselves Rastafari (as opposed to just dreadlocks) who have at least some gangster-istic if not terrorist tendencies. Given the horrifically violent environments that many rasta people come from and have been consciously or unconsciously conditioned by, I'd be surprised if there weren't a few such people. We are all products of our environment to a certain extent. When you grow up surrounded by a gangsta mentality, you might have to adopt that mentality to an extent just to survive. What is really astonishing is not that, it's that so many Rastafari people from such environments do *not* have such a mentality. Really on the whole Rastafari people are an amazingly peaceful people given the conditions many have to deal with.
So I would say this is hyperbole and slander, even if it is based on a kernel of truth (not saying it is or it isn't cos I don't know). I've certainly never met any self-proclaimed Rasta, "gangsta"-ish or otherwise, who professed admiration for bin Laden etc. (who works for the CIA still anyway in my opinion).