To answer your question,They are protecting thieves and anarchists because they are fools in the nth degree and will soon be dead fools.
You can see the AntiFA types in some videos. This is their dream scenario. They are wearing N95 masks, dressed all in black from hood to shoes, wearing backpacks containing who-knows-what. Since masks cannot be banned, maybe backpacks should be banned, along with sticks, poles, rocks, etc.