I was in Dallas when Xyro sent I guess Bear a link to that match with 2 MK's...
There were a few things I noticed about it:
1. Both MK's were planking kinda bad/wrong/sloppy lol. The planking shown in that vid I could easily fart on them as Wario and stage spike them no problem, Dair them, etc.
2. They didn't seem to take the match very seriously. They wouldn't approach much on stage, like look at the beginning they both spawn and kinda mess around lol. They did this a lot of the match, and they both usually gave the other one plenty of room to plank for himself.
Don't get me wrong, I think planking is dumb when done right, but no one in Texas either is willing to do it or they do it wrong and give it beatable openings for most characters. Unless Dojo, Infinity, Me, and maybe Roy start doing this, I think it would be more trouble than benefit to instate a rule on that particular subject.