Nevada: "Official" or "Spanish" Pronunciation?

One of the items I brought back from the 2010 National Book Festival (see related post here) was this tourist map of Nevada. On its front and back flaps, it features a very curious mark over the first letter "a" in the word "Nevada." The mark directs its readers to pronounce the name of the state as "Nevada," using this [æ] sound, rather than "Ne-VAH-da," using this [ɑː] sound. Earlier this summer, some Nevada legislators discussed the idea of declaring the [æ] sound as the "official" pronunciation of the state's name. The implication here is that the "other" pronunciation of the state name, using the [ɑː] sound, is perceived as the "Spanish" pronunciation. (For a more detailed discussion of this issue, see here.)

In the context of this pronunciation debate, I find it curious that this tourist map readily acknowledges that the name of the state is Spanish in origin - it flatly states that "Nevada means 'snow-capped' in Spanish." So why would you go out of your way to discourage people from pronouncing it the "Spanish" way?