The Dish registered trademark is specifically "The mark consists of the word "dish", with the letter "i" consisting of a design element to represent a wireless and/or satllite signal." so I don't think there's any violation unless it's use encroaches on that description.
"DiSH" (lower-case i) originally stood for Digital Sky Highway, because unlike the competition, they intended to build a fleet of satellites to deliver every conceivable service.