To be honest, checking percentages is a bit of a silly thing to do. If I'm Bowser at 110% and somehow I manage to take you with me while you're 111%, you should count it as a tie? Then it's a tie, and you have to redo the match/sudden death (lulz), or else Bowser should lose, even though the attack would've done 18% and get Bowser the lead?
Even worse, if a player can allow Bowser to Bowsercide ON PURPOSE, thereby exploiting the metagame (if it would be decided that Bowser is to lose due to percentage stuff), then how is that different from allowing Bowser to Bowsercide in his favour? The player with the lower percentage gets more control over the direction of the Klaw, depending on how much less percentage he has the more influence he gets. As such, if Bowser Klaws you when you're 150% behind I wouldn't count it unfair to declare Bowser the winner, if somehow Bowser manages to Bowsercide someone who's behind in percentage and manages to get the kill anyway then who's to blame?
Also, I believe that Bowser can do some strange Brawl mechanic thingy which causes him to win anyway. I'd ask Ixis but oh well.
This probably is all very vague (my reasoning that is), I'm tired and just wrote down stuff.
TL;DR: You can't prevent Bowser from exploiting the metagame and allow his opponent to actually do so, consistent and fair results > Sakurai reasoning (none).
edit: Lulz Marc wasn't even talking about Klaw anymore. Let me just say that other move should be addressed invididually, though Inhale moves don't warrant discussion in the first place (game should decide because of the relevant mechanics), only moves that cause both of the players to fall into the abyss no matter what (ie: no matter what the players do) should be discussed, though I do not believe there are any apart of Ganon's sideB and Bowser's Klaw, correct me if I'm wrong.