It's not portraying leftists as half of the electorate. It's just showing two sides, one with Republicans and Democrats and the other with Communists and Anarchists. There's no implications in the image that this is supposed to represent Communists and Anarchists as half of the electorate. You just pulled that out of nowhere. Also, all Communists don't abstain from voting. I'm a Marxist-Leninist, and I voted for Harris(as a means of strategy, not because I like her).