Uh... don't Communists (and a lot of others) always march on May Day? It's Labor Day just about everywhere (except the U.S., even though it commemorates an event in Chicago). It's just that this particular group (of no importance to anyone, anyway) found a bigger group to latch on to. Nothing to get worked up about.
Actually, you have it backward.
It is the communists who have not only started the ruckus in the first place, but are continuing to organize and fund the protestors.
The commies (Socialst Worker's Party) built this protest from the ground up.