So those that are chanting no justice no peace, and those on twitter saying that fires are started because peaceful protests are ignored and change nothing, they're not affiliated with the goals of the protests?

Antifa on the other hand, has not been shown to be a viable terrorist threat, except only to one specific group: white supremacists.

A terror threat that's only a threat to another terror threat, is still operated by terrorists. I.E. Al Queda and ISIS are also enemies. Besides, isn't the big thing going around now is silence is violence and by not joining Antifa you're signalling you're a closeted white supremacist? I don't trust any group that labels everyone not a member as their enemy.