Does castle doctrine mean any guest at a house can kill uninvited guests? Is it awkward because they would have to know the guest was uninvited despite not being the property owner? Would a quick phone call be enough? Assume the uninvited guest is just some random person who entered the house and is not violent.
Does castle doctrine mean any guest at a house can kill uninvited guests?
You have a completely faulty reading of the Castle doctrine (Wikipedia).
The Castle doctrine allows a person... protections and immunities permitting one, in certain circumstances, to use force...
And, those circumstances:
Castle doctrines lessen the duty to retreat when an individual is assaulted within one's own home. Deadly force may either be justified... "when the actor reasonably fears imminent peril of death or serious bodily harm to him or herself or another"...
Castle doctrines may not provide civil immunity, such as from wrongful death suits, which have a much lower burden of proof.
Aspects of the castle doctrine vary according to jurisdiction.