I think it's up to the players to decide if they want to stay in a program. If they put themselves in the portal then all is fine.
However, I think we should all agree that it is unethical for coaches to "recruit" players from other schools, regardless of conference, before that player has publicly declared his interest via the transfer portal.
While these types of things happened long before the portal, it is clearly a case of tampering if recruiting other teams players behind the back of other coaches. Worse still if they are fellow coaches in the same conference.