While you can be mad at your friend, that will not eliminate the very likely occurrence of picking up parasites or disease from bringing ANY adult birds into your flock. Many of us have a closed flock policy for that very reason. Quarantine as well as doing a prophylactic spray or dusting for mites/lice before introducing new birds should be common practice.
BTW, mites and lice can show up in your flock without even introducing new birds to your flock. Rodents and wild birds passing through your yard can introduce the parasites without having direct contact with your birds.