so many on the street have mental, behavioral, social problems. everyone knows that or should know that anyway. animals to street people are family members and companions. it's possible this man somehow saw this as one of his family members being taken from him to "if I can't keep Cletus with me you can't take him" is just evident of his troubles. 
these dogs were probably the only "property" this man had.
this makes me so sad
what about Cletus and the other dog? doesn't anyone know about Cletus? was he hurt bad?