If the therapist thought that he presented an immediate danger to himself, as she had every reason to think, then she is legally obligated to make that call. She may actually believe that the police are more capable than they are, or she may just tell herself that in order to be able to function, but either way, her "checking in" stance is not so hard to understand.

"you are being deliberately disingenuous on this, that much is clear."

It is? I don't think I'm being disingenuous at all, let alone deliberately. Please explain what it is that you think I'm being deceptive about.