The 'evidence' for Nominoe's coronation comes a text from hundreds of years later, suddenly appearing at a time when the status of Dol cathedral was under threat and its challenge to the Metropolitan see of Tours was about to be put to rest. Contemporary documents do not use the title king, not even in the Cartulaire of Redon Abbey, an establishment he was instrumental in founding. It's all a bit like Glastonbury Abbey miraculously discovering the grave of King Arthur just when funds were short .... any legend in a storm.
Nominoe's actions regarding Breton bishops and episcopy of Dol in particular are complicated and difficult to interpret confidently - such is the fascination of the 9th century in Breton history. His son Erispoe certainly has the status of king, a reflection of his achievements against Charles the Bald, but to claim definitively that such an event took place with Nominoe is a travesty, a triumph of competitive tourism over intelligent presentation of historical issues.