I think it's cause he got everyone's hopes up that Miku would appear and then disappointed them by being... well, himself.
Look at Chibi-Miku's expression in the third panel. Sensing someone behind her, Chibi-Miku turns around, anticipating the tearful reunion between her sister and said sister's long-lost friend! An overjoyed expression on her face, she comes face to face with the figure behind her...
Lo and behold! It is Kagamine Len, who has just returned from whatever he was doing before! Chibi-Miku's expression freezes, and somewhere in Marvel Universe Captain America's dead body turns in his super secret coffin.
Len, having gotten Chibi-Miku's hopes up and dashed them against the wall, is swiftly dealt retribution by the vengeful Rin, who had up until this point been forced to deal with KAITO by herself. Oh, where hast thou been, Len?
Either that, or Chibi-Miku actually knew it was Len and the deal that Rin deals to him is the collective anger of the fans towards Minami for stalling yet again... except Minami drew it himself. That makes it meta, or some shit.
I feel that minami is not going to show the reunion until Ruko have to go. Then there will be a big dramtic ending in the strip and the next one would be some cheerful reunion and Ruko turns out to be living next door. Just a hunch.
