Since Dr. Biden never claimed or even implied that she was a physician, there was no justification for honorarary Dr. Epstein who barely scraped through his undergrad program to question her use of the honorific at all.
There was no fraud in her title, and no man is ever entitled to refer to a woman he doesn't even know as "kiddo".
Sounds like honorary Dr. Epstein might have a problem with "Premature Matriculation", if you know what I mean.