Ecofarm's definition comes from an academic, specifically sociological, viewpoint as something such as race is a social construction and thus in order to get a better understanding of race and how it works in the overall society, he examines it through a sociological lens. Rather than use the everyday vernacular, he aims for a specific definition of what racism is and this informs his view of what is or is not racist, something which can be applied to any and all societies. Rather than looking at the actions of the individual, Ecofarm aims to looks at the social institutions within society and how they truly work rather than what they espouse to do or people think that they do. Such a view would lead him to realize that everything that deals with race in America, from the very idea of race to what is racist/racism, are institutionally based and that these institutions back one group over the other. Thus, he differentiates between what racism is and what bigotry is, noting racism is institutionally-based and thus is in and affects the society at large, whereas bigotry is based on the micro-level.
I think that if the situation were reverse, in terms of what race dominated American society (blacks rather than whites), Ecofarm would be stating that what Trayvon said was bigoted.
I am not saying that I agree or disagree with Ecofarm, I am just trying to explain his reasoning behind his definition.
To Ecofarm: Please correct me if I said anything wrong, that you disagree with.