Reports over at WebmasterWorld forums that Adwords Keyword Tool Trademark Blackout. Cline from Aderit Internet Marketing reports that if you use the Google AdWords Keyword Suggestion tool, and plugin a trademarked name, it won't return suggestions. I personally tried this and I am getting suggestions, so maybe this is a limited user test?
I am not sure. But I know Cline knows his stuff and I doubt this is a mistake on his side.
Forum discussion at WebmasterWorld.