The Feds didn't need civil unrest to get involved. They needed evidence of racial motivation, which they looked for and didn't find.
ETA: I should clarify that civil unrest is not only not needed, it's of no help. If other people instigated civil unrest, that would have no legal effect on Zimmerman's case, and in particular would not be grounds for federal prosecution of Zimmerman.
We're probably getting too far into the weeds here.
It is my layperson opinion that it was the civil unrest and racially charged coverage, comments and actions that prompted involvement by federal authorities. It's not my claim that unrest is required or even helpful to the Zimmerman prosecution - though things like civil unrest could be used as an element of federal jurisdiction (18 USC 249).
It is my opinion that the spectre of civil unrest invited federal scrutiny from a public perception (read: political
) standpoint and that more violent and racially charged (as referenced in the statement by Zimmerman's legal team) unrest would lead to more federal scrutiny in this case.
I further speculate that this - along with other issues I discussed - might have restrained the Zimmerman team from making pointed statements when it first became involved in the case and that with that threat somewhat subdued, it frees his legal team from a strategic standpoint to take a more proactive stance.
The First Rule of Holes.
ETA: There's also the possibility that MOM was working under an idealized notion that the irresponsible injection of race into this case would somehow right itself. That was my first impression but as his media strategy progresses I am less inclined toward this conclusion. Either it was a deliberate strategy on his part or he learned from his mistaken ideal quickly enough to recover beautifully. All, of course, in my lay opinion.