What is the ruling on insulting Salafis, or accusing them of personal interests, or hypocrisy and "Tasallum" (feigned Islam), and what is the ruling on excommunicating one who says such things about them?

It is not permissible to mock or ridicule a Muslim, nor to insult them, as this is forbidden by Islamic law. Allah Almighty says: "O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them." Mocking a Muslim for their religion may lead to disbelief (kufr). Accusing people of having hidden intentions is a characteristic of hypocrites, and it is not permissible to accuse a Muslim of hypocrisy or of feigning Islam without proof, for a Muslim is required to judge people by their outward actions, and the inner secrets are for Allah to judge. A Muslim's saying to his Muslim brother, "O hypocrite," falls under the forbidden practice of using offensive nicknames. As for the statement that whoever describes Salafis as hypocrites has committed an act of disbelief (kufr), this is incorrect, as it does not necessarily mean that by saying this, he is mocking Salafism as a methodology or slandering the Companions and their followers.