Voting is the olive branch the owning class extended when the rioting got too close to them. You take that twig, let it ease your conscience however you see fit, then head back out into another riot with a clear mind. It is possible to vote, and also understand that voting is an ultimately meaningless gesture used to guage discontentment of the commoners.
Voting gives credence to the rioting. If you can't be bothered enough to vote, it pulls legitimacy from the riots.