Was Heguri-no-Matori a Usurper?

　In that case, did Heguri-no-Matori encroach on the religious power of the Tennou indeed? Honestly speaking, we cannot find any obvious and absolute proof that he did it rudely. According to descriptions written concisely in the Chronicles of Japan, he only exerted his political competence dictatorially and his son competed with the crown prince for a woman as his private affair. Moreover, in the ancient dual system, there is probability that the crown prince was allocated some political powers apart from the Tennou, the highest officiator. So, we should be prudent to come to the conclusion that he was a usurper who deprived the Tennou of his religious power on this occasion.