Without those rules, he's clearly bannable.
While I think this is blatantly obvious, the problem is that honest, there isn't much proof tournament wise about planking. We have sets here and there, but not tournaments won because of it, or MASSIVE upsets because of it. Sure, on paper it IS broken (I have looked at the edge frame data, it's broken even under frame perfect theoretical terms for the person trying to fight it), but it's sadly not been proven IMO in tournament enough.
Not only that, but then you have the issue of "Ok, with these things allowed, he is Bannable, why not just go ahead and ban him instead of making up a subjective rule that also hurts other characters, and might not even work correctly in the first place?" or "Is Planking a facet of the game that you can reasonably regulate?". I think you could argue for either side in either instance.
MK isn't broken at the top of the metagame, that's already out the window. He's not broken really, just difficult.
The only arguement that should be considered is damaging to the metagame/community.
Here is what is the problem. Almost ALL of these tournaments you see people doing well at like ADHD or Ally, there are Planking rules or rules in place that limit MK.
In a Metagame that involves a Ledge Grab Limit, MK is STILL arguably a bannable character (depends on your criteria, but for a few reasonable criteria sets out there he is bannable). He may not be 100% clear bannable with rules like that in place, but WHY have those rules in the first place?
I've heard the argument "There's nothing wrong with a character to be the best, or to be the most popular/centralize the game". Ok. Now why won't you let this character play with the edge to his hearts content? What's wrong with him being the best at grabbing the edge a lot safely? So what if he centralizes the game around grabbing the edge? How is this a bad thing?
Not only that, but let's assume that it's 100% bad/broken for MK to be allowed to play with the edge like that. In that circumstance, IF YOU ARE BASICALLY SAYING THAT THE CHARACTER, WHEN PLAYING WITH THE EDGE IS TOO GOOD, WHY NOT BAN THE CHARACTER? Think about it: EVERY CHARACTER IN THE GAME CAN PLANK, OR ATTEMPT TO PLANK. The Edge is not something reserved for solely MK. MK is simply playing the game, as it is given to him, as everyone else can attempt, and he just so happens to be the best at it. If it's too powerful for him to do, why make rules that also hamper the opportunity for other characters to attempt it?
Our community is trying to ban or prevent the best character in the game, from using tactics that everyone else can. Sure, maybe they SUCK at it, but oh well, too bad so sad.
Look at Akuma. He was given something that no one else had by a long shot. People deemed him, or the tactic, as broken. What did they do about it? HONESTLY, they could have said "Hey Akuma, don't use Air Fireball/extremely good tool you were given/smart strategy". But they didn't do that. Instead of trying to remove or prevent the moves or tactics that were deemed broken, they simply removed the character. They had an instance where they could have obviously targeted Akuma Exclusively with a rule preventing him specifically from doing that, as he was the only one who could attempt to do it. For MK however, everyone can do it, making it MUCH harder to fairly make a rule that targets him specifically WITHOUT also affecting other characters. Even if you COULD make a rule that was really good, Why make or use that rule in the first place? I don't think people ask that question enough.
Why should MK be any different? Why should we make rules to prevent him from using tactics, if we deem those/him broken? Why not just remove the actual character?
If you deem strategies like Planking or Scrooging with MK as "broken", why even attempt to ban or limit them instead of just getting rid of the character?