**** your title for sounding so intriguing,
no matter what some random kid says no whole character is getting banned... especially not Olimar... (I figured there was some crazy new Olimar trick when i saw the title but since there isn't this is possibly the stupidest thread ever, aside from the ever-coming new "I threw an item with D3" posts)
There is no way they would ban the IC's chain grabs they aren't even close to broken.
As for the IC's chain grab being broken, it is
brawl changed from melee into being a more defensive minded game, so the fact that a character has a 0 to death move that works 100% of the time if done correctly and the technique is quite simple to learn (I tried for about an hour and got 1 strategy of it down pretty consistently) would be considered broken
however despite this point of view I am not against the IC's chain grab as in competitive play a player should be aware of his opponent's strengths and weaknesses and play accordingly. Also i find it somewhat difficult to set-up for the CG since IC's non-grab game is difficult to play at best, and Nana's lag being too much to allow for shield grabbing to be normally effective.
Of course put in the hands of an IC expert, grabbing probably isn't as hard, thus making it up to the opponent to find a way around it.
Conclusion: IC's chain grab is broken, but IC's are not, and without their CG would be a substandard character