The were initially notified because they were advertising to come watch the Super Bowl and listing the admission fee. A big no-no. Also, they were advertising the testimonials of NFL players.
Well then, they were afoul of the law. "Super Bowl" is copyrighted. You'll notice that advertisers that have not bought a license from the NFL never use the term, talking instead about the "big game."
The only thing I question is if the NFL would be able to restrict the screen size so long as there is no admission fee, no collection and no "donations," and no use of the term "Super Bowl." It sounds like fair use to me.