I dunno. It is a pretty dickish move as a fellow student and teacher, and according to the school the club is officially disbanded. But Aki's sister, and judging from an old photo, Mitchie and from what he said, possibly Irei (that might be her in the picture but it's kinda hard to tell, but then again he used to ditch the club to watch her surf) were all part of the previous robotics club. So I guess it is kinda justified for Aki and Mitchie, and maybe for Doc since he invested quite a bit of time in both of them. I guess Kai should've been more pissed, but things got pretty mushy towards the end.
Also, here's hoping for a flash back ep from around the time the photo was taken.