I don't know about Antifa or BLM in general, but anarchists and ancoms generally avoid having to consume and rather build alternative economies and services. As such, they are often targeted by law enforcement. The perception is that they are being protected, but that is propaganda, it's what you were allowed to see. Dig in a bit deeper and you will see the hidden animosity that is present between the US government and the radical left. They wish to bring them down, and the US gov is certainly not stupid enough to not take them seriously.
If an amalgamation of cooperating entities controlling the means of production should be labeled socialism, then does that mean the USA is socialistic? If no, then what is socialism? If yes, then what should be the ancom position of resisting the state and corporate tyranny be described as? If the opposite of socialism is capitalism, then are ancoms capitalistic? If not, then what do ancoms and the US government (or banana republics) have in common?
This is because the leftist position is not pro-immigration for the sake of itself. The left and the right aren't defined by the policies they believe in, but rather in their respective worldviews. The left gravitates towards a stateless (nationless) classless moneyless society, while the right considers those fundamental. This is, of course, assuming a lot, since "the left" and "the right" are such broad labels, they're often almost meaningless.