I can accept the Kyuubi acting the way he is.

All through the series we are told he's totally evil, that he wants to only destroy, however, we never actually see him act like this. I don't buy the Kyuubi being in control when Naruto grows a 4th tail. Every time we go that route it's not because of the Kyuubi, but because of Naruto's own blind rage. All Kyuubi has wanted since the beginning of this series is to be free, and who can blame him? He's imprisoned in someone that until not too long ago, he only thought wanted to use him for power(and for the most part, this has been true via actions).

I don't believe that it's a large leap of judgement that the Kyuubi has grown a certain level of respect for Naruto, and likewise I believe that Naruto is beginning to respect his jailed friend. If anything, this series has shown that Naruto has the ability to break down the chains of just about everyone's hatred; he has been the catalyst of change. To say it's off the mark for the Kyuubi to act like this after finally having some level of dialogue(Other then, "U MAD BRO? Break this seal and I'll show you mad.") with this catalyst isn't crazy, it's logical.