I wonder if client will continue to benefit in such a relationship . unless an ethical T who feels they can no longer/don't want to help the client n terminate. In that case , client ll feel rejected and be in more pain. It's easier for client to just go back n be in this unhealthy dynamic and get their needs met for as long as they can. Its better than nothing right ? But eventually the relationship will end. That's the reality.
I feel it will be unethical for a T to take back such a client when T's heart is not in the right place. N client might feel they can change T's mind. For this relationship to work...both parties have to be involved and willing to work towards a goal.

Also I think it takes a great deal of courage and strength to go back...after seeing hints of rejection. You are putting yourself out there and taking a risk .