And so it happened that race riots have struck, again, in 2015, in Baltimore:
Many regular people believe this vicious slander (and others pretend to, for certain personal or political reasons). The Martian would see people in the highest levels of government promoting this idea, more-or-less explicitly. People from the most prestigious and tone-setting positions in the national media (say, the New York Times Editorial Board), too, the Martian would see constantly pushing the idea.
The Martian would be baffled. Why would top officials in a government promote ideas that undermine the authority of their own police, and more generally undermine the entire system they lead, that they control? He would conclude that such a bizarre system cannot be sustainable.
And so hundreds of buildings and vehicles were destroyed, who-knows-how-many-millions'-worth looted, and the loss of prestige as the entire world sees another U.S. race riot.
Another Black activist interviewed on TV said (something close to) "People in our community are angry. And just wait until we don't have a Black president anymore, then things will get worse."
What the Martian would think upon hearing this, I won't even begin to guess.