^fyi, Tsunku is not producing this unit. In fact, he might not even produce the new KSS unit.
The indies single was initially a challange to see if they were ready to debut. I always assumed that they won't be releasing a major debut single until Momoko is freed from Berryz Koubou because they will be blessed with promotions by then. I mean, both Momoko and Manakan were promoting a lot in Hokkaido (both TV and radio) for this Hokkaido Harocon.
I guess the possivite feedback from the group / songs made Satoda Mai realized that the girls may not be 100% polished, but are ready for their major debut. In my opinion, it's smart to release this single since it is still fresh and catchy to their current audience. I mean, only a few hundred of people will be the indies single prior to general release (if they ever decided to), while their major debut will have thousands of copies sold.
Also, I don't know why people (particularly from H!O) are assuming they are ditching their indies single, since no one mentioned cancelling the release. All indie singles within H!P are a waiting game.
I mean, the KSS album was properly announce literally a few days before it's release.