seems like your asking two questions.

why the blood rituals?

why central florida?

as for the first question, that is simply how blood rituals work, or sacrificial rituals of that sort. if you look into and study that phenomena you can get a real grip on how powerful it would be to magnify a simple blood ritual to the scale of say an event with unsuspecting mass deaths like the events of september eleventh 2001.

second question, pretty irrelevant in my opinion i think you are just looking to hard into some minor cases of manipulated events involving deaths.