I don't think the Kuuga part is of importance, since it was just a pilot series, and he had been doing Sentai for 5+ years.
Perhaps he's been a fan of Kamen Rider and finally had a chance to join with Agito and knowing what Hibiki was about made him not want to do it...
Or...
I was digging around on his Japanese Wiki page and it mentions something about Atsushi and Magiranger, but Google Chrome's translate to English made a... Well pretty hard to understand.
However he's apperently shown up at a kindergarten in the Momotaros costume :laugh: