I think it could. As the provision is apparently being understood by law enforcement, once the declaration is made that there's a riot, just having a mask on and not dispersing immediately would make you guilty of this further offence. It could be a mask of George Bush, the Prime Minister, or some world leader that's being worn for legitimate purposes of political dissent. I think once the declaration is read, if the person is wearing the mask and doesn't immediately disperse, he's guilty of not dispersing when directed as well as this offence.
On May 8th, 2012. See this statement in context.