That doesn't seem to hold up in court, though.
In that case, a woman completed a four year post-doctorate fellowship in psychology at Yale, had her Ph.D. for education published in a psychology journal, taught psychology at college, studied under psychologists, and was a member of the American Psychological Association for years. She did not, however, have a license to practice psychology in Texas. She would sometimes give psychological advice and, when she ran for a political position, she said she was an attorney and psychologist on her website. The Texas State Board of Examiners of Psychologists demanded she stop saying she was a psychologist because she wasn't licensed to be one in Texas.
The court basically said it was an infringement of her first amendment rights. She wasn't giving advice to a client. Her background suggests calling herself a psychologist is not misleading. In fact, the court said that commercial speech is speech that "proposes" a commercial transaction, not speech for profit. So even receiving compensation for speech isn't necessarily commercial in nature and can be protected.
So, at the end of it, he probably has a case that his speech is protected. There seems to be precedent.