>>724683490
>Why would they be overconfident if the page posted before clearly states that his ki is getting bigger?
Not only was his ki getting bigger, he was also getting bulkier. For that brief moment, there seemed to be a correlation. So, for Kid Buu to end up emerging as a scrawny little midget, they probably assumed that he lost that increase in ki or something.

Anyway, if there was even an inkling of doubt, Shin says it himself. Absorbing the kais REDUCED his power, so, naturally, expelling Fat Buu would cause him to gain power, as the kais were inside Fat Buu.