Thanks Tsumanne! I was wondering the same thing as kiratsuki, here
is another news link about the boycott issue.
The article mentions that the major anime companies and others will be organizing a different event, "Anime Contents Expo" on the same weekend at Makuhari Messe. Here
is a link to the event home page.
The English side of the homepage is minimal on information but the Japanese side has a cosplay link containing the rules and stuff. It looks like they will have changing areas that cost 500 yen but no cloak area so they ask you to take care of your belongings. No military uniforms (Sorry T).
It'll be a stretch from Osaka the weekend before so I'm not sure about either events for me.