I imagine that anything SG said on any given day on the Today Show has the potential to send an unemployed (able) key board warrior into a fit.
But... the miffed keyboarder then retaliates not by the SOP- sending an expletive laden email to the Show, but by kidnapping SG's mother? Like yourself, I just don't see it.
The factor in the Olympian social dynamics: This is still pre Olympics, so SG could not have been perceived as 'dissing the hometown hero with a medal.
Even with medals, the Olympics have been in a slow decline for decades. Sure, there are plenty of fans out there. But, over all interest has still declined and fewer people see successful Olympians as national figures, hometown super heroes, or personal idols.
Though it just takes one person who does have those views to meltdown and act on them in an extreme way, I share your opinion in that, while its possible, it just does not seem very likely.