Branding police.
Even spectators will not be allowed to wear clothing with a logo not of an official sponsor. All competing logos removed from the area.
And like all these insane actions, the government provides the enforcement muscle. Corporate state at it's craziest.
http://www.coyoteblog.com/coyote_blog/2012/05/corporate-state-and-the-olympics.html
[BTW The author of that blog post is no MJ…