There IS no valid argument behind "I win against everyone, but lose to MK, so let's ban him!". Most of the pro-ban players just follow the majority of the people to not be shoved aside into the smaller, anti-ban group. Sort of like a need to 'fit in', which they also see boosted by one less headache at tournaments, ending up with two birds killed with one stone.
I am completely anti-ban. MK is winnable. My counter for MK is Kirby. Kirby can destroy MK if the same MK doesn't know what to watch out for. Couple that with knowledge on what works against MK's choices, and you have yourself a winning situation.
If the pro-ban community is choosing to ban MK out of self-gratification, then this poll has no meaning at all. In fact, as soon as the SB-R decided on making this poll, Genesis was practically told to let down on the MKs, or else they'll ban him. If the 'top' players know what's good for them, they'll sacrifice this tourney and its winnings by using a different character (at least, some of them), so they can keep using it on the many, many tourneys that will take place until the next tier list will be done. It's a smart investment, sacrifice $50.00 to earn hundreds more over the course of time that is left between this upcoming tier list, and the next... So, as soon as this poll appeared and made public the consideration of MK's ban, MK's usage should've dumbed down even a little.
If that won't solve the MK problem for Genesis, then the only thing that will warrant his banning is seeing the top 10 placings dominated by MK, yet again... Which will not help the community in any way, as another character will appear and start dominating the tournament scene... Maybe with not the same flair, but domination nonetheless, then even though we won't ban them because they'll have legal counterpicks, people will start complaining abou that character. It's a never-ending cycle.
Mks can be beaten. If YOU can't beat any MKs, then it's your problem. The top players, however, are the ones who refuse to lose. Learn to deal with the characters, learn to sit back and watch before rushing into a dsmash/tornado, and you'll see the tides turn.
Anti-ban, and staying anti-ban.