A property owner (or in this case, really anyone who lays claim to a property, since a state that could issue official deeds does not exist) still has the right to defend their property using violent means if necessary.
Okay, but if there isn’t a state, who is to say the workers don’t have the right to protect their surplus labor value from theft by seizing the means of production, through violence if necessary?
This is one of the reasons why anarcho capitalism is an incoherent ideology. People who believe in it think that the right of private property is just something everyone agrees should be held sacred, when it only exists because of state violence.