Dealing with the Rafidah in the workplace and the restaurant, and returning their salam

Question:
In the Shaykh’s country, we have some Rafidah (Twelver Shi'ah) and social people from these lands in our workplace, and we are confused about how to deal with them. They interact with us and ask about the craft if they are with us according to need. We say to the gathering: “Do not return the salam to them.” I read that sitting with them is a sin, and some say that they should be treated like the hypocrites because they claim Islam and affirm the books, so they do not return the salam to them or greet them. And some see that they are disbelievers, so they do not return the salam to them, and they do not mix with them in the restaurant, considering it from the virtue of the one who is present.

Answer:
As for the salam, you do not initiate it, but if they greet you, you return it. As for mixing with them in the restaurant, if the mixing is with affection, love, and relaxation, this is not permissible.
As for if the mixing is just each taking what he needs from the restaurant without there being any joking or laughter with them, then there is no harm in it. And if you sit separately and they sit separately, that is better. Sit with your brothers and they sit separately; this is better. Yes, the important thing is that you do not relax with them, take them as friends, or take them as companions. Yes.
As for merely sitting in the restaurant while they are sitting in it, and you hate them and do not relax with them, there is no obstacle to that. Whoever prays with you, let them pray with you. Do you drive them away from prayer? Let them pray.