He wasn't assaulting anyone and wasn't trespassing if the daughter invited him in. The father could 'uninvite him' but in any case, isn't justified in shooting him.
Per the entire article, Guzman initated the assualt of Reed, and Guzman had been forbidden to enter the house without an adult present. The daughter is not an adult and has no right to change the rules set by the father, who is the homeowner.