Not really.
A ) Pro-ban doesn't want to go against MLG or the SBR. If one or the other approves it, all it takes is one TO per region to stand up, and the pro-ban players will flock. Ultimately, people are lazy; if someone does the work for them, they'll be happy.
B ) Just because pro-ban goes to MK tournaments
now, you know, when there are no alternatives, does
not mean they will when there is another option for them.
C ) My personal guess is that most of the people that hate MK enough to ban him like
the game enough to not stop playing, which is why they aren't boycotting right now.
Give the people the option, and they'll go to MK-banned events (AN notwithstanding). Of course, AN doesn't
want to give the option because they know Xyro's scenario is actually pretty possible, and they don't want to look like tools for being whiny children. Therefore, block a temp-ban and don't let people have the option to out them for the tools they are.