I don't know that I would say a T is being "inflexible" if she reinforces reasonable boundaries in an effort to best help her clients. For example, if a client has ET, by refusing to accept a "romantic" gift, she is refusing to enable the transference. It seems that, in that situation, she is actually helping the client even if it hurts in the short run.

Of course, there are times when a T could be inflexible. For example, if a T refused to accept a hand-made "thank-you" card because she has a strict no-gifts policy, that would seem to be overkill.