And it's not just Spanish-- I've seen this come up on the EU forums as well, when someone posts in French or German. Why is Blizzard so opposed to players posting in their native language? Of course, as Timbal says, not everyone can know every language, but Timbal knew enough Spanish to realize the original thread (called "server latino") was asking for new realms. And this is 2007-- is it too much to ask for one Blizzard forums employee that speaks Spanish, or in the EU, French or German? They may not know enough to actually answer the questions in that language, but they should know enough to police players who are speaking in that language, maybe in a special foreign language section of the forum.
Now, also according to forums policy (but also not listed in the "guidelines"), you're also not supposed to request new realms, so even if the thread was in English, it would have been closed anyway. And if someone speaking a foreign language is somehow being obscene, that doesn't belong on the forums either. But it's unfair for people who have legitimate questions or requests and want to posit them in their native language to be shut down by Blizzard automatically. Nine million people play this game, and it's very likely a large number of them don't speak English as their native language-- for Blizzard to completely ignore them on the forums is a poor decision.
Update: Our terrific commenters point out that there are French, Spanish, and German forums for the EU servers. But the fact remains that Blizzard closes, without second thought, any thread started in a foreign language on the US servers.